LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 


Class 


OF  THE 

UNIVERSITY 

OF 


INTRODUCTION 


TO  THE 


RARER    ELEMENTS. 


BY 


PHILIP  E.   BROWNING,   PH.D., 

Atsistant  Professor  of  Chemistry  >  Kent  Chemical  Laboratory, 
Yalt  Univertity. 


SECOND   EDITION,  THOROUGHLY    REVISED. 

FIRST    THOUSAND 


NEW  YORK: 

JOHN  WILEY  &  SONS. 

LONDON:  CHAPMAN  &  HALL,  LIMITED. 

1908. 


V 


Copyright,  1903,  1908, 

BY 

PHILIP  E.  BROWNING. 


Chr  «?rirnltfu  £rrB« 
Kobrrt  Srumnumfc  anb  vtompang 


PREFACE   TO   THE    SECOND   EDITION. 


DURING  the  five  years  that  have  elapsed  since  the 
appearance  of  the  first  edition  of  this  book,  the  chemistry 
of  the  rarer  elements  has  undergone  no  small  measure 
of  development.  In  that  division  of  the  field  known  as 
the  rare  earths,  Dr.  C.  Richard  Bohm's  Darstellung  der 
seltenen  Erden,  in  two  volumes  of  about  five  hundred  pages 
each,  has  given  to  chemists  some  conception  of  the  mass 
of  work  which,  up  to  that  time,  had  been  done ;  and  since 
the  publication  of  those  volumes  the  activity  along  this 
line  has  not  abated.  During  the  same  period  the  study  of 
the  radio  elements  has  developed  a  well-defined  department 
of  research,  and  the  rare  metals  vanadium,  tungsten  and 
tantalum  have  become  important  members  of  the  chemical 
family  on  account  of  their  technical  applications.  These 
examples  illustrate  the  recent  advances  which  demand 
recognition  even  in  a  handbook  of  small  compass. 

In  presenting  this  edition  the  author  makes  grateful 
acknowledgment  to  Dr.  B.  B.  Boltwood  of  Yale  Univer- 
sity for  his  contribution  of  the  chapter  on  Radio  Elements, 
to  Dr.  C.  L.  Parsons  of  New  Hampshire  College  for  kindly 
suggestions  regarding  the  revision  of  the  chapter  on 
Beryllium,  to  members  of  the  author's  recent  classes  in 
the  rarer  elements  for  their  experimental  work  leading 
to  the  selection  of  separation  methods,  to  the  critics  of  the 
first  edition  for  useful  hints,  and  to  his  wife  for  much 
painstaking  work  upon  the  preparation  of  the  manuscript 
for  publication. 

NEW  HAVEN,  Conn.,  October,  1908. 


188495 


PREFACE   TO  FIRST    EDITION. 


THIS  small  volume,  prepared  from  material  used  by  the 
author  in  a  short  lecture  course  given  at  Yale  University, 
is  intended  to  serve  as  a  convenient  handbook  in  the  intro- 
ductory study  of  the  rarer  elements ;  that  is,  of  those 
elements  which  are  not  always  taken  up  in  a  general  course 
in  chemistry.  No  attempt  has  been  made  to  treat  any  part 
of  the  subject  exhaustively,  but  enough  references  have 
been  given  to  furnish  a  point  of  departure  for  the  student 
who  wishes  to  investigate  for  himself.  Experimental  work 
has  been  included  except  in  the  case  of  those  elements  which 
are  unavailable,  either  because  of  their  scarcity  or  because 
of  the  difficulty  of  isolating  them. 

The  author  has  drawn  freely  upon  chemical  journals  and 
standard  general  works.  In  his  treatment  of  the  rare  earths 
he  has  made  especial  use  of  Herzfeld  and  Korn's  Chemie 
der  seltenen  Erden  and  Truchot's  Les  Terres  Rares,  works 
which  he  gladly  recommends.  He  gratefully  acknowledges 
the  valuable  assistance  of  his  wife  in  preparing  this  ma- 
terial for  the  press. 

NEW  HAVEN    CONN.,  April,  1903. 


TABLE   OF   CONTENTS. 


CHAPTER  PA«E 

I.  THE  ALKALIES i 

II.  BERYLLIUM 17 

III.  THE  RADIO  ELEMENTS 25 

IV.  THE  RARE  EARTHS 35 

V.  GALLIUM,  INDIUM,  THALLIUM 82 

VI.  TITANIUM,  GERMANIUM 96 

VII.  VANADIUM,  NIOBIUM,  TANTALUM 107 

VIII.  MOLYBDENUM,  TUNGSTEN,  URANIUM 125 

IX.  SELENIUM,  TELLURIUM 144 

X.  THE  PLATINUM  METALS,  GOLD 161 

XI.  THE  RARE  GASES  OF  THE  ATMOSPHERE 190 

XII.  TECHNICAL  APPLICATIONS 196 

XIII.  QUALITATIVE  SEPARATION. 202 

vii 


INDEXES  TO  THE   LITERATURE  OF  CERTAIN 
ELEMENTS. 


Beryllium,  Parsons.     In  press. 

Caesium,  Rubidium,  Lithium,  and  Thallium,  Index  to  the  Literature  of} 
Fraprie.     In  preparation. 

Cerium,  Index  to  the  Literature  of  (1751-1894);  Magee.     Smithsonian 
Misc.  Coll.  (1895),  No.  971. 

Columbium,    Index   to   the   Literature   of    (1801-1887);   Traphagen. 
Smithsonian  Misc.  Coll.  (1888),  No.  663. 

Didymium,  Index  to  the  Literature  of  (1842-1893);  Langmuir.     Smith- 
sonian Misc.  Coll.  (1894),  No.  972. 

Gallium,  Index  to  the  Literature  of  (1876-1903);  Browning.     Smith- 
sonian Misc.  Coll.  (1904),  No.  1543. 

Germanium,  Index  to  the  Literature  of  (1886-1903) ;  Browning.     Smith- 
sonian Misc.  Coll.  (1904),  No.  1544. 

Indium,  Index  to  the  Literature  of  (1863-1903);  Browning.     Smithson- 
ian Misc.  Coll.  (1905;,  No.  1571. 

Lanthanum,  Index  to  the  Literature  of  (1839-1894);  Magee.     Smith- 
sonian Misc.  Coll.  (1895),  No.  971. 

Lithium,  vid.  Caesium. 

Niobium  or  Columbium,  vid.  Columbium. 

Platinum  Metals,  Bibliography  of  (1748-1897);  Howe.     Smithsonian 
Misc.  Coll.  (1897),  No.  1084. 

Rare  Earths,  Bibliographic  der  seltenen  Erden;  Meyer.    Hamburg. 
Leopold  Voss,  1905. 

Rubidium,  vid.  Caesium. 

Thallium,  Index  to  the  Literature  of  (1861-1896);  Doan.    Smithsonian 
Misc.  Coll.  (1899),  No.  1171.    Also,  vid  Caesium. 

ii 


x         INDEXES   TO    THE  LITERATURE  OF  CERTAIN  ELEMENTS, 

Thorium,  Index  to  the  Literature  of  (1817-1902);  Jouet.     Smithsonian 

Misc.  Coll.  (1903),  No.  1374. 
Titanium,  Index  to  the  Literature  of  (1783-1876);  Hallock.     Annals  of 

the  N.  Y.  Academy  of  Sciences  (1876),  i,  53. 
Uranium,  Index  to  the  Literature  of  (i  789-1885) ;  Bolton.     Smithsonian 

Report  for  1885,  Part  i,  915. 
Vanadium,  Index  to  the  Literature  of  (1801-1877);  Rockwell.     Annals 

of  the  N.  Y.  Academy  of  Sciences  (1879),  i,  133. 
Vanadins,  Die  Literatur  des  (1804-1905);  Prandtl.     Hamburg,  Leopold 

Voss,  1906. 
Yttrium  Group,  Index  to  the  Literature  of  the  Rare  Earths  of;  Dales. 

In  preparation. 
Zirconium,   Index  to  the  Literature  of   (1789-1898);  Langmuir  and 

Baskerville.     Smithsonian  Misc.  Coll.  (1899),  No.  1173. 

Attention  is  called  also  to  the  following  monographs: 

Die  Physikalisch-Chemischen  Eigenschaften  des  metallischen  Selens; 
Marc.  Pub.  by  Leopold  Voss,  Hamburg,  1907. 

Die  Chemie  des  Thoriums;  Koppel.  Sammlung  chemischer  Vortrage, 
Band  VI.  Pub.  by  Ferd.  Enke,  Stuttgart,  1901. 

Studien  uber  das  Tellur;  Gutbier.  Pub.  by  C.  L.  Hirschfeld,  Leipzig, 
1902. 

La  Chimie  de  L'Uranium  (1872-1902);  Oechsner  de  Coninck.  Pub. 
by  Masson  et  Cie.,  Paris,  1902. 

The  Analytical  Chemistry  of  Uranium;  H.  Brearley.  Pub.  by  Long- 
mans, Green  &  Co.,  London  and  New  York,  1903. 

Die  analytische  Chemie  des  Vanadins;  Valerian  von  Klecki.  Pub.  by 
Leopold  Voss,  Hamburg,  1894. 

Le  Vanadium;  P.  Nicolardot.     Pub.  by  Masson  et  Cie.,  Paris. 

Das  Vanadin  und  seine  Verbindungen;  Fritz  Ephraim.  Pub.  by  Ferdi- 
nand Enke,  Stuttgart,  1904. 


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THE   RARER  ELEMENTS 


CHAPTER   I. 
THE  ALKALIES. 
LITHIUM,  Li,   7.03. 

Discovery.  In  1817  Arfvedson,  working  in  Berzelius's 
laboratory  upon  a  petalite  from  Uto,  Sweden,  discovered 
an  alkali  which  he  found  to  differ  from  those  already  known 
in  the  following  particulars:  (i)  in  the  low  fusing  points 
of  the  chloride  and  sulphate;  (2)  in  the  hydroscopic  char- 
acter of  the  chloride ;  and  (3)  in  the  insolubility  of  the  car- 
bonate. In  his  analysis  of  the  mineral  it  had  remained 
associated  with  sodium,  not  being  precipitated  by  tartaric 
acid.  To  the  newly  discovered  element  the  name  Lithium 
was  given,  from  Az'0o?,  stone,  because  it  differed  from 
sodium  and  potassium  in  having  a  mineral  rather  than 
a  vegetable  origin  (Ann.  der  Phys.  u.  Chem.  (1818),  xxix, 
229 ;  Ann.  Chim.  Phys.  [2]  x,  82).  It  has  since  been  found, 
however,  not  only  in  the  mineral  kingdom,  but  in  the 
vegetable  and  animal  kingdoms  also. 

Occurrence.     Lithium  is  found  combined  as  follows: 

(i)  In  minerals: 

Petalite,          LiAl(Si2O5)2,  contains  2-5%*  Li20. 

SpodumeneJ  LiAl(SiO3)2,  "        4-8% 

Lepidolite,      R3Al(SiO3)3,                           "        4-6%       " 
Zinnwaldite,  (K,Li)3FeAl3Si5O16(OH,F)2,  "        3-4%       " 
Cryophyllite,  complex  silicate,   vid.   Zinnwaldite,  contains 
4-5%  Li20. 

*  In  the  tabulation  of  percentages  the  nearest  whole  numbers  have  generally 
been  used  in  this  book. 

f  The  more  important  mineral  sources  are  indicated  by  italics. 


2  THE  RARER  ELEMENTS. 

Irvingite,  complex  silicate,  contains  4-5%  Li2O. 
Polylithionite,  complex  silicates,  vid.  Zinnwaldite,  contains 

about  9%  Li2O. 

Beryl,  BCjAl^SiOj),,      contains  0-1%    Li/). 

Triphylite,       Li(Fe,Mn)PO4,  8-9%      " 

Lithiophilite,  Li(Mn,Fe)PO4,         "         8-9%     " 
Amblygonite,  Li(AlF)PO4,  "         8-10%    " 

Small  amounts  of  lithium  are  found  also  in  some  varie- 
ties of  tourmaline,  in  epidote,  muscovite,  orthoclase,  and 
psilomelane. 

(2)  In  certain  mineral  waters,  among  which  are  Durk- 
heim,    Kissingen,    Baden-Baden,    Bilin,    Assmannshausen, 
Tarasp,  Kreuznach,  Salzschlirf,  Aachen,  Selters,  Wildbad, 
Ems,     Homburg,     Karlsbad,     Marienbad,     Egger-Franzen- 
bad,  Wheal  Clifford,  Bad  Orb,  Sciacca,  Salsomaggiore. 

(3)  In    seaweed,    tobacco,    cacao,    coffee,    and    sugar- 
cane; in  milk,  human  blood,  ancl  muscular  tissue;  in  me- 
teorites.    It  has  been  detected  also  in  the  atmosphere  of 
the  sun. 

Extraction.  Lithium  may  be  extracted  from  minerals 
by  the  following  methods: 

(1)  From  triphylite  or  Uthiophilite.    The  coarsely  ground 
mineral  is  dissolved  in  hydrochloric  acid  to  which  nitric 
acid  is  gradually  added,  and  the  solution  obtained  is  treated 
with  a  sufficient  amount  of  ferric  chloride  to  unite  with  all 
the  phosphoric  acid  present.     This  solution  is  evaporated 
to  dryness  and  the  residue   is  extracted  with  hot  water. 
The  extract  thus  obtained  is  treated  with  barium  sulphide, 
to  remove  the  manganese  and  the  last  traces  of  iron.     The 
barium  is  removed  by  sulphuric  acid,  and  the  filtrate  is 
evaporated  with   oxalic   acid   and   ignited.      The   alkalies 
remain  as  carbonates  (Muller). 

Lithium  may  be  separated  from  the  other  alkalies  by 
treating  the  mixed  carbonates  with  water,  lithium  carbonate 
being  comparatively  insoluble. 

(2)  From  lepidolite  (or  any  other  silicate).     The  mineral  is 


LITHIUM.  3 

melted  at  /ed  heat  in  a  crucible,  the  melted  mass  is  cooled 
rapidly  in  water  and  pulverized.  Sufficient  water  is  added 
to  give  the  material  the  consistency  of  paste.  Hydrochloric 
acid  of  specific  gravity  1.2,  equal  in  weight  to  the  weight 
of  the  mineral  taken,  is  gradually  added,  with  stirring. 
The  mass  is  allowed  to  stand  for  twenty-four  hours.  It  is 
then  heated  again  to  about  100°  C.,  with  stirring,  and  a 
second  portion  of  acid  equal  to  the  first  is  added.  Upon 
several  hours'  heating  the  silica  separates  in  the  form  of 
powder,  and  after  treatment  with  nitric  acid  'to  oxidize 
the  iron,  the  soluble  material  is  separated  by  filtration  from 
the  silica.  The  filtrate  is  heated  to  the  boiling-point  and 
treated  with  sodium  carbonate,  which  precipitates  iron, 
aluminum,  calcium,  magnesium,  manganese,  etc.  These 
are  removed  by  filtration,  and  the  liquid  is  evaporated  to 
a  small  volume  and  filtered  again  if  necessary.  Lithium 
carbonate  is  precipitated  by  more  sodium  carbonate 
(Schrotter). 

The  Element.  A.  Preparation.  Elementary  lithium  may 
be  obtained  by  subjecting  the  fused  chloride  or  bromide  to 
electrolysis.  Because  of  its  volatility  it  cannot,  like  sodium 
and  potassium,  be  prepared  by  heating  the  carbonate. 

B.  Properties.  Lithium  is  a  metallic  element  which  has 
a  silvery-white  luster  and  which  oxidizes  in  the  air,  though 
more  slowly  than  potassium'  and  sodium.  It  decomposes 
water  at  ordinary  temperatures,  and  is  light  enough  to 
float  in  petroleum.  Its  melting-point  is  180°  C. ;  its  specific 
gravity  is  0.59. 

Compounds.  A.  Typical  forms.  The  following  are 
typical  compounds  of  lithium: 

Oxide,  Li2O. 
Hydroxide,  LiOH. 
Carbonate,  Li2CO8. 
Chloride,  LiCl. 
Chlorate,  LiClO8  +  o.5H2O. 


THE  R4RER  ELEMENTS. 


Perchlorate, 

Bromide,  LiBr. 

Bromate,  LiBrO,. 

Iodide,  LiI  +  3H2O. 

lodate,  LiIO3  +  o.sH2O. 

Periodate,  LiIO4. 

Fluorides,  LiF;  LiF-HP. 

Nitride,  LiN3. 

Nitrite,   LiNO2  +  o.5H2O. 

Nitrate,  LiNO3. 

Sulphide,  Li2S. 

Sulphite,  Li2SO3. 

Sulphates,  Li2SO4;  KLiS04;  NaLiSO4;  etc. 

Phosphates,  LiH2PO4;  Li3PO4  +  o.sH20;  Li4P2O7. 

Carbide,  Li2C2. 

Silicofluoride, 


B.  Characteristics.  Most  of  the  salts  of  lithium  are 
easily  soluble  in  water;  the  principal  exceptions  are  the 
carbonate  and  the  phosphate,  which  are  difficultly  soluble. 
Lithium  resembles  sodium  more  closely  than  it  resembles 
the  other  alkalies,  in  that  it  does  not  form  an  insoluble 
chloroplatinate,  nor  a  series  of  alums.  The  nitrate  and 
the  chloride  are  soluble  in  alcohol.  The  compounds  of 
lithium  color  the  flame  brilliant  crimson. 

Estimation.  Lithium  is  usually  weighed  as  the  sul- 
phate or  chloride. 

Separation.  Lithium  may  be  separated  from  the  other 
members  of  the  alkali  group  (i)  by  the  ready  solubility  of  its 
chloride  in  amyl  alcohol  (Gooch,  Amer.  Chem.  Jour,  ix,  33)  ; 
(2)  by  the  solvent  action  of  absolute  ethyl  alcohol  upon 
the  chloride;  (3)  by  the  insolubility  of  the  phosphate  in  the 
presence  of  ammonia  and  ethyl  alcohol  (Benedict,  Amer. 
Chem.  Jour,  xxxn,  480)  ;  (4)  by  the  comparative  insolubility 
of  the  carbonate;  (5)  by  the  solubility  of  the  fluosilicate 
(Reichard,  Chem.  Ztg.  xxix,  861)  ;  (6)  by  the  insolubility  of 


EXPERIMENTAL    WORK  ON  LITHIUM.  5 

the  sulphate  in  magnesium  chloride  formed  by  the  addition 
of  magnesium  sulphate  to  mother  liquors  containing  chlo- 
rides (Siebert,  Pharm.  Centr.  XLVI,  368) ;  (7)  by  the  solubility 
of  the  chloride  in  pyridine  (Kahlenberg,  Jour.  Amer.  Chem. 
Soc.  xxiv,  401). 

EXPERIMENTAL  WORK  ON  LITHIUM. 

Experiment  i.  Extraction  of  lithium  salts  from  tri- 
phylite  or  lithiophilite.  Dissolve  25  to  50  grm.  of  finely 
powdered  mineral  in  common  hydrochloric  acid,  add 
sufficient  nitric  acid  to  oxidize  the  iron,  and  enough  ferric 
chloride  to  combine  with  all  the  phosphoric  acid  present. 
Evaporate  to  dryness  and  extract  with  hot  water.  Treat 
the  extract  with  barium  hydroxide  in  slight  excess.  Filter, 
add  sulphuric  acid  to  complete  precipitation  of  barium 
sulphate,  and  filter  again.  Convert  the  sulphates  present 
into  carbonates  by  the  careful  addition  of  barium  carbonate, 
filter,  acidify  the  filtrate  with  hydrochloric  acid,  evaporate 
to  dryness,  and  extract  the  lithium  chloride  with  alcohol. 

(Lithium  salts  may  be  extracted  also  from  the  mother- 
liquor  after  the  extraction  of  caesium  and  rubidium  salts 
from  lepidolite.  The  liquor  is  treated  with  barium  car- 
bonate in  excess  and  is  then  boiled  and  filtered.  The 
filtrate  is  acidified  with  hydrochloric  acid,  evaporated  to 
dryness,  and  extracted  with  alcohol.) 

Experiment  2.  Precipitation  of  lithium  phosphate 
(Li3PO4) .  To  a  solution  of  a  lithium  salt  add  sodium  phos- 
phate in  solution. 

Experiment  3.  Precipitation  of  lithium  carbonate 
(Li2CO3) .  To  a  few  drops  of  a  concentrated  solution  of  a 
lithium  salt  add  sodium  carbonate  in  solution. 

Experiment  4.  Solvent  action  of  alcohol  upon  lithium 
salts.  Try  the  action  of  ethyl  or  amyl  alcohol  upon  a  little 
dry  lithium  nitrate  or  chloride. 


6  THE  R4RER  ELEMENTS. 

Experiment  5.  Flame  and  spectroscopic  tests  for  lithium. 
(a)  Dip  a  platinum  wire  into  a  solution  of  a  lithium  salt  and 
hold  in  a  Bunsen  flame.  Note  the  color. 

(b)  Observe  the  lithium  flame  by  means  of  the  spectro- 
scope. Note  the  bright  crimson  line  between  the  potas- 
sium and  sodium  lines. 

Experiment  6.  Negative  tests  of  lithium  salts.  Note 
that  hydrogen  sulphide,  ammonium  hydroxide,  ammonium 
carbonate  acting  upon  dilute  solutions,  chloroplatinic  acid, 
and  sodium  cobaltic  nitrite  give  no  precipitate  with  lithium 
salts. 


RUBIDIUM,  Rb,   85.5. 

Discovery.  Rubidium  was  discovered  by  Bunsen 
and  Kirchhoff  in  1861,  by  means  of  the  spectroscope,  in 
the  course  of  some  work  upon  a  lepidolite  from  Saxony 
(J.  B.  (1861),  173;  Chem.  News  in,  357).  The  alkaline 
salts  had  been  separated  by  the  usual  methods  and  pre- 
cipitated with  platinic  chloride.  The  precipitate,  when 
examined  with  the  spectroscope,  showed  at  first  only  the 
potassium  lines.  When  it  had  been  boiled  repeatedly 
with  water,  however,  the  residue  gave  two  violet  lines 
situated  between  the  strontium  blue  line  and  the  potas- 
sium violet  line  at  the  extreme  right  of  the  spectrum. 
These  increased  in  strength  as  the  boiling  continued,  and 
with  them  appeared  several  other  lines,  among  which 
were  two  almost  coincident  with  the  potassium  red  line  (a) 
at  the  extreme  left.  These  lines,  observed  for  'the  first 
time,  marked  the  discovery  of  an  element ;  because  of  their 
color  Bunsen  gave  it  the  name  Rubidium,  from  the  Latin 
rubidus,  the  deepest  red. 

Occurrence.  Rubidium,  like  caesium,  is  widely  distrib- 
uted, but  in  very  small  quantities.  It  is  found 


RUBIDIUM.  7 

(1)  In  minerals: 

Lepidolite,       RsAl(SiO8)3,        contains  0.7-3.0%  Rb2O. 

Leucite,  KAl(SiO3)2,  "         traces 

Spodumene,    LiAl(SiO3)2, 

Triphylite,       Li(Fe,Mn)PO4, 

Lithiophilite,  Li(Mn,Fe)PO4, 

Carnallite,       KMgCl3-6H2O, 

Mica  and  orthoclase  contain          "  * ' 

(2)  In  certain  mineral  waters,  among  which  are  the 
following:  Ungemach,   Ems,   Kissingen,   Nauheim,   Selters, 
Vichy,  Wildbad,  Kochbrunnen  (Wiesbaden),  Durkheim. 

(3)  In  beet-root,  many  samples  of  tobacco,  some  coffee 
and  tea,   ash  of  oak  and  beech,   crude  cream  of  tartar, 
potashes,  and  mother-liquor  from  the  Stassfurt  potassium 
salt  works. 

Extraction.  Rubidium  may  be  extracted  with  caesium 
from  lepidolite  (vid.  Extraction  of  Caesium). 

The  Element.  A.  Preparation.  Elementary  rubidium 
may  be  obtained  (i)  by  heating  the  charred  tartrates  to  a 
white  heat  (Bunsen) ;  (2)  by  reducing  the  hydroxide  or  the 
carbonate  with  magnesium  (Winkler,  Ber.  Dtsch.  chem. 
Ges.  xxm,  51);  (3)  by  reducing  the  hydroxide  with  alumi- 
num (Beketoff). 

B.  Properties.  Rubidium  is  a  soft  white  metal  which 
melts  at  38°  C.  It  takes  fire  in  the  air,  burning  to  the  oxide. 
It  decomposes  water.  Its  specific  gravity  is  1.52. 

Compounds.       A.    Typical   forms.       The   following  are 
typical  compounds  of  rubidium: 
Oxide,  Rb2O. 
Hydroxide,  RbOH. 
Carbonates,   Rb2CO3;  RbHCOa. 
Chloride,  RbCl. 
Double     chlorides,      HgCl2-2RbCl;     HgCl2-2RbCl  +  2H2O; 

2HgCl2  •  RbCl ;  4HgCl2  -  RbCl ;  PbCl4  •  2RbCl ;  2PbCl2  -  RbCl ; 


8  THE  RARER  ELEMENTS. 

PbCl2  -  2RbCl  +  o.  sH2O ;      BiCl3  -  6RbCl ;      BiCl3  -  RbCl  + 

4H2O;     CdCl2.2RbCl;     2AsCl3-3RbCl;     3SbCl3-5RbCl; 

2SbCL  -  3RbCl ;         SbCl3  -  RbCl ;         2SbCl3  -  RbCl  +  H2O ; 

MnCl2  •  2RbCl  +  2H2O ;  ZnCl2  •  2RbCl ;  MgCl2  •  RbCl  +  6H2O ; 

AuCl3  -  RbCl ;          TeCl4  -  2RbCl ;         T1C1,  -  3RbCl  +  H2O ; 

TlCl3.2RbCl  +  H20. 
Chlorate,  RbClO3. 
Perchlorate,  RbClO4. 
Bromides,  RbBr;  RbBrr 
Double  bromides,    2PbBr2-RbBr;  PbBr2-2RbBr  +  o.5H2O; 

2AsBr3 .  3RbBr ;  2SbBr3  -  3RbBr ;          AuBr3  -  RbBr ; 

TeBr4-2RbBr;  TlBr3-3RbBr  +  H2O;  TlBr3-RbBr  +  H2O. 
Iodides,  Rbl ;  RbI3. 
Double  iodides,  Agl  -  2RbI ;  PbI2  -  Rbl  +  2H2O ;  2 Asls  •  3RbI ; 

2SbI3  •  3RbI ;  TeI4  •  2RbI ;  Til,  •  Rbl  +  2H2O. 
lodates,  RbIO3;  RbIO3-HIO3;  RbIO3-2HIO3. 
Nitride,  RbN3. 

Nitrates,  RbNO3;  3RbNO3-Co(NO3)3  +  H2O. 
Cyanide,  RbCN. 

Sulphates,  Rb2SO4;  RbHSO4;  Rb2S2O7;  Rb2O-8SO3, 
Alums,          RbAl(SO4)2  +  i2H2O;          RbFe(SO4)2  +  i2H2O; 

RbCr(SO4)2  +  i2H2O;    Rb2S04-Ti2O3-3SO3  +  24H2O. 
Chloroplatinate,  Rb2PtCl6. 
Silicofluoride,  Rb2SiF6. 

B.  Characteristics.  The  rubidium  compounds  are  very 
similar  to  those  of  potassium  and  caesium  (vid.  Caesium). 
Among  the  important  insoluble  salts  are  the  perchlorate 
(RbClOJ,  the  silicofluoride  (Rb2SiF6),  the  chloroplati- 
nate  (Rb2PtCl6),  the  bitartrate  (RbHC^CJ^CU),  the  alums 
(RbAl(SO4)2+i2H20  and  RbFe(SO4)2+i2H2O),  and  the 
cobaltic  nitrite  (Rb3Co(NO2)6,  typical).  The  salts  of  rubid- 
ium color  the  flame  violet.  The  spectrum  gives  two  lines 
in  the  violet  to  the  right  of  the  caesium  lines  (Rba  and 
Rb/?);  also  two  lines  not  so  distinct  in  the  dark  red  (Rbf 
and  Rb<5),  near  the  potassium  red  line,  at  the  left  of 
the  spectrum. 


CAESIUM.  9 

Estimation,    Separation,    and    Experimental  Work.      Vid. 
Caesium. 


CESIUM,  Cs,  132.9. 

Discovery.  Caesium  was  discovered  in  1860  by  Bun- 
sen  and  Kirchhoff  while  they  were  engaged  in  the  spectro- 
scopic  examination  of  a  mother-liquor  from  the  waters  of 
Durkheim  spring  (Pogg.  Annal.  cxui,  337;  Chem.  News  n, 
281).  After  the  removal  of  the  strontium,  calcium,  and 
magnesium,  by  well-known  methods,  and  of  the  lithium 
as  far  as  possible  by  ammonium  carbonate,  the  mother- 
liquor  was  tested,  and  gave,  in  addition  to  the  potassium, 
sodium,  and  lithium  lines,  two  beautiful  blue  lines  never 
before  observed,  near  the  strontium  blue  lines.  Bunsen 
gave  the  name  Caesium  to  the  newly  discovered  element, 
from  the  Latin  caesius,  the  blue  of  the  clear  sky. 

Occurrence.  Caesium  is  found  in  combination  as 
follows : 

(1)  In  minerals: 

Pollucite,  H2Cs4Al4(SiO3)9,  contains  3i-37%Cs2O. 
L^Wo/^,LiK(Al(OH,F)2).Al(SiO3)3,containso.2-o.7%Cs2O. 
Beryl,  Be3Al2(SiO3)6,  contains  0-3%  Cs2O. 

(2)  In  certain  mineral  waters,  among  which  are  Durk- 
heim  ( i  liter  contains  about  0.21  mg.  RbCl  and  0.17  mg. 
CsCl),     Nauheim,    Baden-Baden,    Frankenhausen,   Kreuz- 
nacher,  Bourbonne  les  Bains,   Monte  Catino,  Wheal  Clif- 
ford. 

Extraction.  Of  the  methods  in  use  for  the  extraction 
of  caesium  the  following  may  serve  as  examples: 

(i)  From  pollucite.  The  finely  powdered  mineral  is 
decomposed  on  a  water-bath  with  strong  hydrochloric  acid. 
To  the  acid  solution  antimony  trichloride  is  added,  which 
precipitates  the  double  chloride  of  antimony  and  caesium 
(3CsCl-2SbCl3)  (Wells,  Amer.  Chem.  Jour,  xxvi,  265). 


10  THE  RARER  ELEMENTS. 

Or  the  acid  solution  may  be  treated  with  a  solution  of  lead 
chloride  containing  free  chlorine.  This  precipitates  a 
double  chloride  of  caesium  and  tetravalent  lead  (2CsCl  -PbCl4) 
(Wells,  Amer.  Jour.  Sci.  [3]  XLVI,  186). 

(2)  From   any   silicate.      The    mineral  is    heated   with 
a  mixture  of  calcium  carbonate  and  ammonium  chloride, 
and  the  fused  mass  is  cooled  and  extracted  with  water. 
fThe  liquid  is  then  evaporated  to  a  small  volume,  and  sul- 
phuric acid  is  added  to  precipitate  the  calcium  as  the  sul- 
phate.    After  filtration,  evaporation  is  continued  until  the 
greater  part  of  the  hydrochloric  acid  has  been  expelled. 
Sodium  or  ammonium  carbonate  is  then  added  to  complete 
the  removal  of  the  calcium  salt.     Upon  the  addition  of 
chloroplatinic  acid  the  caesium  and  rubidium  are  precipi- 
tated as  the  salts  of  that  acid.     By  the  action  of  hydrogen 
upon  these  salts  the  platinum  is  precipitated,  while  the 
caesium  and  rubidium  chlorides  are  left  in  solution. 

(3)  From  lepidolite.     The  mineral  is   decomposed  by 
heating  with  a  mixture  of  calcium  fluoride  and  sulphuric 
acid   (vid.  Experiment   i). 

The  Element.  A.  Preparation.  Elementary  caesium 
may,  be  obtained  (i)  by  heating  caesium  hydroxide  with 
aluminum  to  redness  in  a  nickel  retort  (Beketoff,  Bull. 
Acad.  Petersburg  iv,  247) ;  (2)  by  heating  caesium  hy- 
droxide with  magnesium  in  a  current  of  hydrogen  (Erd- 
mann  and  Menke,  Jour.  Amer.  Chem.  Soc.  xxi,  259,  420); 
(3) )  by  heating  caesium  carbonate  with  magnesium  in  a 
current  of  hydrogen  (Graefe  and  Eckardt,  Zeitsch.  anorg. 
,Chem.  xxu,  158). 

B.  Properties.  Caesium,  the  most  positive  of  the  metals, 
is  silvery  white  and  soft.  It  takes  fire  quickly  in  the  air, 
burning  to  the  oxide.  It  melts  at  26°  C.  Like  the  other 
alkaline  metals  it  decomposes  water.  Determinations  of 
its  specific  gravity  range  from  1.88  to  2.4. 


CESIUM.  n 

Compounds.    A.     Typical   forms.     The    following    are 
typical  compounds  of  caesium: 
Oxide,  Cs2O. 
Hydroxide,  CsOH. 
Carbonates,  Cs2COs;  CsHCO3. 
Chloride,  CsCl. 
Double   chlorides,    AgCl-CsCl;    AgCl-CsCl;    HgCl2-CsCl; 

HgCl2.2CsCl;  HgCl2.3CsCl;  2HgCl2.CsCl;  sHgd.-CsCl; 

PbCl4-2CsCl;    PbCl2-4CsCl;    PbCl2-CsCl;    2PbCl2-CsCl; 

2BiCl3-3CsCl;  BiCl,-3CsCl;  CuCl^CsCl;  CuCl2-2CsCH- 

2H2O;   2CuCl2-3CsCl  +  2H2O;   CuCl2-CsCl;   Cu2Cl2-CsCl; 

Cu2Cl2  •  3CsCl ;        Cu2Cl2  •  6CsCl  +  2H2O ;         CdCl2  •  2CsCl ; 

CdCl2-CsCl;    2AsCl3-3CsCl;    2SbCl3 - 3CsCl ;    SnCl2-CsCl; 

Fe2Cl6-6CsCl;  CoCl2-3CsCl;  CoCl2-2CsCl;  CoCl2-CsCl  + 

2H2O;        NiCl2-2CsCl;        NiCl2-CsCl;        MnCl2-2CsCl; 

2MnCl2-2CsCl  +  5H2O;  MnCl2 - 2CsCl  +  3H2O ;  MnCl2-CsCl 

+  2H2O;  MnCl2-2CsCl  +  H2O;  ZnCl2-3CsCl;  ZnCl2-2CsCl; 

MgCl2-CsCl  +  6H2O;    AuCl3.CsCl;    AuCl3-CsCl  +  o.5H2O; 

PtCl4-2CsCl;    PtCl2-2CsCl;    PdCl2-2CsCl;    TeClr2CsCl; 

T1C13  •  3CsCl  +  H20 ;      T1C13  -  2CsCl ;      T1C13  -  2CsCl  +  H2O ; 

2TlCl3-3CsCl. 

Bromides,  CsBr;  CsBr3;  CsBr5. 
Double  bromides,  HgBr2  •  CsBr ;  HgBr2  •  2CsBr ;  HgBr2  •  3CsBr ; 

2HgBr2-CsBr;  PbBr2  -  4CsBr ;  PbBr2  -  CsBr ;  2PbBr2-CsBr; 

CuBr2  -  2CsBr ;  CuBr2  -  CsBr ;  CdBr2  -  3CsBr ;  CdBr2  -  2CsBr ; 

CdBr2  •  CsBr ;  2 AsBr3  -  3CsBr ;  CoBr2  -  3CsBr ;  CoBr2  •  2CsBr ; 

NiBr2  •  CsBr ;  ZnBr2  -  3CsBr ;  ZnBr2  •  2CsBr ;  MgBr2  •  CsBr  + 

6H2O;     AuBr3-CsBr;      TeBr4«2CsBr;      2TlBr3  •  3CsBr ; 

TlBr3-CsBr. 

Iodides,  Csl;  CsI3;  CsI6. 
Double  iodides,   HgI2-CsI;         HgI2-2CsI;         HgIa-3CsI; 

2HgI2-CsI ;  3HgI2- 2CsI ;  PbI2.CsI ;  CdI2-3CsI ;  CdI2-  2CsI^ 

CdI2-CsI  +  H2O;     2AsI3-3CsI;     CoI2-2CsI;     ZnI2.3CsI; 

ZnIa-2CsI;  TeI4-2CsI;  Til, -Csl. • 


12  THE  R4RER  ELEMENTS. 

Mixed   halides,    HgCs3Cl3Br2;      HgCs2Cl2Br2;      HgCsClBr2; 

Hg5CsClBr10;      HgCs3Br3I2;      HgCs2Br2I2;      HgCsBrI2; 

HgCs2Cl2I2;  PbCs4(ClBr)6;  PbCs(ClBr)3;  Pb2Cs(ClBr)8. 
Double  fluorides,  2CsF  •  ZrF4 ;  CsF  •  ZrF4  +  H2O ;  2CsF  -  3ZrF4  + 

2H2O. 

lodates,  CsIO3;  2CsIO3-I2O5;  2CsIO3-I2O5+2HIO3. 
Nitride,  CsN3  (Jour.  Amer.  Chem.  Soc.  xx,  225). 
Nitrates,  CsNO3;  3CsNO3 -Co(N03)3  +  H2O. 
Sulphates,  Cs2SO4;  CsHSO4;  Cs2S2O7;  Cs2O-8SOr 
Alums,  CsAl(SO4)2  +  i2H20;        Cs2SO4.Mn3(SO4),+  24H2O; 

Cs2S04  -Ti2O3  •  3SO3  +  24H2O. 
Fluosilicate,  Cs2SiF6. 
Chromates,  Cs2CrO4;  Cs2Cr2O7. 
Chloroplatinate,  Cs2PtCl6. 
Cobaltic  nitrite,  Cs3Co(NO2)6,*  typical. 

B.  Characteristics.  With  few  exceptions  the  caesium 
compounds  are  soluble  in  water.  They  closely  resemble 
the  potassium  and  rubidium  compounds,  being  for  the 
most  part  isomorphous  with  them.  A  comparison  of  the 
solubilities  of  the  alums  and  also  of  the  chloroplatinates 
of  the  three  elements,  at  a  temperature  of  i5°-i7°C., 
follows : 

100  parts  of  water  will  dissolve 

CsAl(SO4)2  +i2H2O,    0.62  parts;   Cs2PtCl6,  0.18  parts. 
RbAl(SO4)2  +  i2H2O,    2.30      "       Rb2PtCl6,  0.20      " 
KA1(SO4)2  +i2H2O,  13.50      "         K2PtCl6,  2.17      " 

Among  the  important  insoluble  salts  are  the  chloroplatinate 

*  Cs  may  be  partly  replaced  by  Na. 


C&S1UM.  13 

(Cs2PtCl6),  the  alum  (CsAl(SO4)2  +  i2H20),  the  cobaltic 
nitrite  (Cs3Co(N02)6,  typical),  and  the  double  chlorides 
with  tetravalent  lead  (PbCl4-2CsCl),  tetravalent  tin 
(2CsCl •  SnCl4 ?) ,  and  trivalent  antimony  (sCsCl  •  2SbQ3) .  The 
salts  of  caesium  color  the  flame  violet.  The  spectrum  shows 
two  sharply  defined  lines  in  the  blue,  designated  on  the  scale 
as  Csa  and  Cs/?. 

Estimation  of  Caesium  and  Rubidium.  Caesium  and  ru- 
bidium may  be  estimated  in  general  by  the  methods  applied 
to  potassium.  They  are  usually  weighed  as  the  normal  sul- 
phates, after  evaporation  of  suitable  salts  with  sulphuric 
acid  and  ignition  of  the  products;  other  methods,  however, 
such  as  the  chloroplatinate  and  chloride  methods,  are  pos- 
sible. They  may  be  weighed  with  a  fair  degree  of  accuracy 
as  the  acid  sulphates,  after  evaporation  with  an  excess  of 
sulphuric  acid,  and  heating  at  25o°-27o°  C.  until  a  constant 
weight  is  obtained  (Browning,  Amer.  Jour.  Sci.  [4]  xn,  301). 
They  may  also  be  estimated  by  precipitation  with  sodium 
cobaltic  nitrite,  decomposition  of  the  cobaltic  nitrites  with 
hydrochloric  acid,  and  precipitation  of  the  perchlorates  by  a 
30%  perchloric  acid  solution  (Montemartini,  Gaz.  chim. 
ital.  xxxin  (n),  189;  Chem.Zentr.  1904  (i),  119).  Rubidium 
may  be  estimated  by  means  of  the  spectroscope  by  com- 
paring the  intensity  of  the  spectrum  lines  obtained  from  a 
definite  amount  of  solution  of  rubidium  salt  to  be  estimated 
with  that  of  the  lines  obtained  from  a  definite  amount 
of  a  solution  of  known  strength  (Gooch  and  Phinney, 
Amer.  Jour.  Sci.  [3]  XLIV,  392). 

Separation  of  Caesium  and  Rubidium.  These  metals  belong 
to  the  alkali  group.  From  sodium  and  lithium  they 
may  be  separated  (i)  by  chloroplatinic  acid,  with  which 
they  form  insoluble  salts;  and  (2)  by  aluminum  sulphate, 
with  which  they  form  difficultly  soluble  alums.  From 
potassium  they  may  be  separated  by  the  greater  solubility 
of  the  potassium  alum  and  chloroplatinate  in  water. 


14  THE  RARER  ELEMENTS. 

Caesium  and  rubidium  may  be  separated  from  each 
other  (i)  by  the  difference  in  solubility  of  the  chloroplati- 
nates;*  (2)  by  the  difference  in  solubility  of  the  alums;* 
(3)  by  the  formation  of  the  more  stable  and  less  soluble 
tartrate  of  rubidium;  and  (4)  by  the  solubility  of  caesium 
carbonate  in  absolute  alcohol.  Probably  the  most  satis- 
factory methods,  however,  are  those  suggested  by  Wells; 
they  depend  upon  the  insolubility  of  the  following  salts: 
caesium  double  chloride  and  iodide  (CsClJ)  (Amer.  Jour. 
Sci.  [3]  XLIII,  17),  caesium-lead  chloride  (Cs2PbCl6)  (ibid. 
[3]  XLVI,  1 86),  and  caesium-antimony  chloride  (Cs3Sb2Cl9) 
{Amer.  Chem.  Jour,  xxvi,  265). 

EXPERIMENTAL  WORK   ON    CESIUM  AND 
RUBIDIUM. 

Experiment  i.  Extraction  of  c&sium  and  rubidium  salts 
from  lepidolite.  Mix  thoroughly  in  a  lead  or  platinum 
dish  100  grm.  of  finely  ground  lepidolite  with  an  equal 
amount  of  powdered  fluorspar.  Add  50  cm.3  of  com- 
mon sulphuric  acid  and  stir  until  the  mass  has  the 
consistency  of  a  thin  paste.  Set  aside  in  a  draught  hood 
until  the  first  evolution  of  fumes  (SiF4  and  HF)  has  nearly 
ceased.  Heat  on  a  plate  or  sand-bath  at  a  temperature 
of  2oo°-3oo°  C.  until  the  mass  is  dry  and  hard.  Pulverize 
and  extract  with  hot  water  until  the  washings  give  no 
precipitate  on  the  addition  of  ammonium  hydroxide  to 
a  few  drops.  Evaporate  the  entire  solution  to  about 
100  cm.3  and  filter  while  hot  to  remove  the  calcium  sul- 
phate. Set  the  clear  filtrate  aside  to  crystallize.  The 
crystals,  consisting  of  a  mixture  of  potassium,  caesium, 
and  rubidium  alums,  with  some  lithium  salt,  should  be 
dissolved  in  about  100  cm.3  of  distilled  water,  and  allowed 
to  recrystallize.  This  process  of  recrystallization  should 

*  Vid.  p.  12. 


EXPERIMENTAL    WORK   ON  CESIUM  AND  RUBIDIUM.         15 

be  repeated  until  the  crystals  give  no  test  before  the  spec- 
troscope for  either  lithium  or  potassium.  The  amount  of 
caesium  and  rubidium  alums  obtained  will  of  course  vary 
with  the  variety  of  lepidolite  used.  An  average  amount 
of  the  mixed  alums  of  potassium,  caesium,  and  rubidium 
from  the  first  crystallization  would  be  10  grm.  The  pure 
caesium  and  rubidium  alums  finally  obtained  should  be 
about  3  grm.  (Robinson  and  Hutchins,  Amer.  Chem.  Jour. 
vi,  74).  Lithium  may  be  extracted  from  the  mother-liquor 
(vid.  Experiment  i,  Lithium). 

Experiment  2.  Preparation  of  ccesium  and  rubidium 
sulphates  (Cs2SO4;  Rb2SO4).  Dissolve  in  water  a  crystal 
of  the  caesium  and  rubidium  alums  obtained  from  lepido- 
lite, add  a  few  drops  of  ammonium  hydroxide,  and  boil. 
Filter  off  the  aluminum  hydroxide  and  evaporate  the 
filtrate  to  dryness.  Ignite  until  the  ammonium  sulphate 
is  removed,  dissolve  in  a  f$w  drops  of  water,  filter,  and 
evaporate  to  dryness.  Sulphates  of  caesium  and  rubidium 
will  remain. 

Experiment  3.  Preparation  of  the  carbonates  of  c&sium 
and  rubidium  (Cs2CO3 ;  Rb2CO3).  Dissolve  in  water  a  crystal 
of  caesium  and  rubidium  alums  obtained  from  lepidolite, 
add  an  excess  of  barium  carbonate,  and  boil.  Filter  off 
the  alumina,  barium  sulphate,  and  excess  of  barium 
carbonate.  Pass  a  little  carbon  dioxide  through  the  clear 
filtrate  and  boil  to  remove  traces  of  barium  salt.  Filter. 
Carbonates  of  caesium  and  rubidium  will  remain  in  solution. 

Experiment  4.  Formation  of  the  double  chloride  of 
casium  and  tetravalent  lead  (2CsCl  -PbCl4).  To  a  few 
cm.3  of  a  one  per  cent,  solution  of  a  caesium  salt  add  a  few 
drops  of  the  reagent  obtained  by  warming  lead  dioxide 
with  hydrochloric  acid  and  allowing  the  solution  to  stand 
until  cool.  Make  a  similar  experiment,  using  a  rubidium 
salt  in  place  of  the  caesium  salt.  Note  the  absence  of  pre- 
cipitation in  this  case. 


16  THE  RARER  ELEMENTS. 

Experiment  5.  Precipitation  of  the  double  chloride  of 
c&sium  and  antimony  (3CsCl-2SbCl3).  To  a  few  cm.3  of 
a  one  per  cent,  solution  of  a  caesium  salt  add  some  anti- 
mony trichloride  in  solution  and  evaporate  to  a  small 
volume.  The  double  chloride  will  be  precipitated  on  cool- 
ing. Repeat  the  experiment,  using  a  rubidium  salt.  Note 
the  absence  of  precipitation  in  this  case. 

Experiment  6.  Precipitation  of  the  double  salt  ccesium 
chloride  and  stannic  chloride  (2CsCl-SnCl4).  Make  an  ex- 
periment similar  to  Experiment  5,  using  stannic  chloride 
in  the  place  of  antimonious  chloride.  Note  the  separa- 
tion of  the  double  chloride  on  cooling.  Make  a  similar 
experiment,  using  a  rubidium  salt. 

Experiment  7.  Precipitation  of  the  chloroplatinates  of 
ccesium  and  rubidium  (Cs2PtCl6;  Rb2PtCl6).  To  a  few 
cm.3  of  a  solution  of  a  caesium  salt  add  a  few  drops  of  a 
solution  of  chloroplatinic  acid.  Make  a  similar  experiment 
with  a  solution  of  a  rubidium  salt. 

Experiment  8.  Precipitation  of  the  cobaltic  nitrites  of 
ccEsium  and  rubidium.  Try  the  action  of  a  solution  of  sodi- 
um cobaltic  nitrite  upon  separate  solutions  of  caesium  and 
rubidium  salts. 

Experiment  9.  Flame  tests  for  ccesium  and  rubidium. 
Dip  the  end  of  a  platinum  wire  into  a  solution  of  a  caesium 
salt  and  test  the  action  of  the  flame  of  a  Bunsen  burner 
upon  it.  Repeat,  using  a  rubidium  salt. 

Experiment  10.  Spectroscopic  tests  for  ccesium  and 
rubidium.  Test  solutions  of  caesium  and  rubidium  salts 
before  the  spectroscope.  Note  the  twin  blue  lines  of  the 
caesium  spectrum  and  the  twin  violet  lines  of  the  rubidium. 

Experiment  1 1 .  Negative  tests  of  c&sium  and  rubidium. 
Note  that  hydrogen  sulphide,  ammonium  sulphide,  and 
ammonium  carbonate  give  no  precipitates  with  salts  of 
caesium  and  rubidium. 


CHAPTER  II. 

BERYLLIUM,  Be,  9.1. 

Discovery.  In  the  year  1 797,  Vauquelin  discovered  beryl- 
lium or  glucinum  in  the  mineral  beryl  (Ann.  de  Chim.  xxvi, 
155).  After  having  removed  the  silica  in  the  usual  manner, 
he  precipitated  with  carbonate  of  potassium,  and  treated  the 
precipitate  with  a  solution  of  caustic  potash.  The  greater 
part  of  the  precipitate  dissolved,  leaving  a  residue  which  he 
found  to  consist  of  a  small  amount  of  iron  oxide  and  an 
oxide  which  dissolved  in  sulphuric  acid.  This  solution  gave, 
on  evaporation,  irregular  crystals  having  a  sweetish  taste 
and  forming  no  alum  with  potassium  sulphate.  In  his 
early  articles  Vauquelin  refers  to  the  oxide  as  "la  terre 
du  B£ril,"  which  the  German  chemists  translated,  "  Beryl  - 
erde."  The  sweet  taste  suggested  for  the  new  element 
the  name  Glucinum,  from  yXvxvZ,  sweet.  The  name  Beryl- 
lium, from  the  chief  source,  beryl,  has  been  more  gen- 
erally used. 

Occurrence.     Beryllium  occurs  in  minerals  as  follows: 

Beryl,  BegAl^SiO^e,          contains  n-i5%BeO. 

Chrysoberyl,  BeAl2O4,  "         19-20%    " 

Bertrandite,  Be2(Be-OH)2Si2O7,      "        40-43%    " 

Phenacite,  Be2SiO4,  "        44-46%    " 

Leucophanite,  Na(BeF)Ca(SiO3)2,      "         10-12%    " 

Meliphanite,  NaCa2Be2FSi3O10         "        10-14%    " 

Epididymite,  HNaBeSi3O8,  "         10-11%    " 

Euclase,  Be(Al-OH)SiO4,          "         17-18%    " 

Helvite  or  danalite,   R5(R2S)(SiO4)3,  "        13-14%     " 

17 


i8 


THE  RARER  ELEMENTS. 


FeBe2Y2Si20io,              contains    5~u%BeO. 

Be(Mn,Ca,Fe)Si04, 

16-17% 

tt 

complex  silicate, 

14-15% 

tt 

it              n 

"    circa  14% 

" 

tt             tt 

o-.3% 

tt 

n             tt 

5-6% 

tc 

it             it 

o-4% 

11 

U                           ft 

0-1% 

" 

complex  silico-tantalate, 

"      circa  i% 

it 

NaBePO4, 

"        19-20% 

u 

Ca(Be(OH,F))PO4, 

"        15-16% 

tt 

Be(BeOH)B03, 

"        53-54% 

"  tt 

ErNb04. 

"      circa  .6% 

ft 

complex  carbonate, 

"           9-Jo% 

ft 

Gadolinite, 

Trimerite, 

Cyrtolite, 

Alvite, 

Allanite, 

Muromonite, 

Erdmanite, 

Foresite, 

Arrhenite, 

Beryllionite, 

Herderite, 

Hambergite, 

Sipylite, 

Tengerite, 


Beryllium  is  found  also  in  traces  in  some  monazite 
sands  and  aluminous  schists,  and  in  some  mineral  waters. 

Extraction.  Beryllium  is  generally  extracted  from  beryl 
by  one  of  the  following  methods : 

(1)  The    mineral   is   fused  with   sodium   or  potassium 
hydroxide  (vid.  Experiment  i). 

(2)  The  finely  ground  mineral  is  fused  with  three  times 
its  weight  of  potassium  fluoride.    The  fused  mass  is  treated 
with  strong  sulphuric  acid  and   warmed;  by  this  process 
the  silica  is  removed  as  silicon  fluoride,  and  the  alumina 
and  potash  are  united  to  form   the  alum,  which  may  be 
crystallized  out  on  evaporation.     The   beryllium  remains 
in  solution  as  the  sulphate,  and  may  be  removed  by  the 
treatment  described  in  Experiment  i . 

(3)  The  mineral   is  fused  with  calcium  fluoride.     This 
process  is  in  general  the  same  as  the  one  indicated  in  the 
second  method,  except    that  calcium  sulphate  is  formed 
and  must  be  removed    (Lebeau,  Chem.  News  LXXIII,  3). 

(4)  The   mineral   is    decomposed    by   fusion    (a)    with 


BERYLLIUM.  19 

sodium  and  potassium  carbonates,  or  (b)  with  acid 
potassium  sulphate. 

The  Element.  A.  Preparation.  Elementary  beryllium 
may  be  obtained  (i)  by  bringing  together  the  vapor  of 
the  chloride  and  sodium  in  a  current  of  hydrogen  (De- 
bray,  Ann.  Chim.  Phys.  (1855)  XLIV,  5);  (2)  by  fusing  the 
chloride  with  potassium  (Wohler,  Pogg.  Annal.  xm,  577); 
(3)  by  heating  the  chloride  in  a  closed  iron  crucible  with 
sodium  (Nilson  and  Pettersson,  Ber.  Dtsch.  chem.  Ges.  xi, 
381 , 906) ;  (4)  by  electrolyzing  the  double  fluoride  of  beryllium 
and  sodium  or  potassium  (Lebeau) . 

B.  Properties.  The  element  beryllium  is  dark  steel-gray 
in  color.  At  ordinary  temperatures  unchanged  in  air  and 
in  oxygen,  it  burns  brightly  to  the  oxide  when  heated  in 
either.  It  does  not  decompose  hot  or  cold  water.  When 
heated  it  combines  readily  with  fluorine,  chlorine,  bromine 
and  iodine.  It  is  soluble  in  dilute  and  in  concentrated  acids; 
also  in  potassium  hydroxide  with  the  liberation  of  hydrogen. 
Determinations  of  its  specific  gravity  range  from  1.75  to 

i.8S. 

Alloys  of  beryllium  with  many  of  the  common  metals 
are  known,  as  are  also  alloys  with  chromium,  molybdenum 
and  tungsten  (Lebeau) .  An  alloy  of  -copper  and  beryllium 
containing  from  .5%  to  1.3%  beryllium  is  very  sonorous. 

Compounds.  A.  Typical  forms.  The  following  are 
typical  compounds  of  beryllium : 

Fluorides,  BeF2;  BeF2.2NaF;  BeF2.2KF;  BeF2.2NH4F. 
Chlorides,    BeCl2;    BeCl2.AuCl3;    BeCl2.FeCl3.H2O;    BeCl2. 

CrCl3.H2O;    3BeCl2.Tl2Cl6;     BeCl2.2lCl3.8H2O;     BeCl2. 

PtCl2.5H2O;       BeCl2.PtCl4.8H20;      BeCl2.PdCl2.6H20; 

BeCl2.PdCl4.8H2O. 
Bromide,  BeBr2. 
Iodide,  BeI2. 
Hydroxide,  Be(OH)2. 


20  THE  RARER  ELEMENTS. 

Oxide,  BeO. 

Sulphide,  BeS. 

Cyanides /  BePt(CN)4.4H2O;     BeMg2Pt3(CN)i2;      Be?tDr2 

(CN)4. 

Carbides,  Be2C;  3Be2C.B6C. 
Sulphates,    BeSO4;     BeS04.2H2O;     BeS04.4H20;     BeS04. 

K2S04.2H2O;      BeSO4.K2SO4.KHSO4.4H2O;      3BeS04. 

2Na2S04.i2H2O;  BeSO4.(NH4)2S04.2H2O. 
Sulphites,  BeS03.H20;  BeSO3.2H2O;  2BeSO3.K2SO3.9H20; 

2BeS03.(NH4)2S03.4H2O. 
Selenate,  BeSe04.4H20. 
Selenites,  BeSeO3.H2O;  BeSeO3.2H2O. 
Nitrate,  Be(NO3)2.4H2O. 
Phosphates,   BeHPO4.3H2O;    BeKPO4;    BeNaP04;    BeNa2 

(NH4)2(P04)2. 

Antimonate,  Be(Sb03)2.6H2O. 
Carbonate,  xBeCO3/yBe(OH)2. 
Silicates,  BeSi03;  Be3Al2(Si03)6. 
Aluminate,  Be(A102)2. 
Methyl,  Be(CH3)2. 
Ethyl,  Be(C2H5)2. 
Propyl,  Be(C3H7)2. 

Acetates,  Be(C2H302)2;  Be40(C2H302)6. 
Acetylacetonate ,  Be(C5H702)2. 
Oxalates,  BeC204.3H20;  BeC2O4.K2C2O4;  etc. 
Tartrates,  BeC4H4O6.3H20;     KBeC4H3O6;    K2Be4C8H4Oi3. 

7H20;  Na2Be4C8H4Oi3.ioH20. 
Succinate,  BeC4H404.2H20. 
Racemates,  (NH4)2Be4C8H4Oi3.ioH2O ;    (NH4)2Be4C8H4Oi3. 

ioH2O. 

Malates,  K2Be4C8H6Oi2.5H2O;  Na2Be4C8H6Oi2.7H20;  etc. 
Formate,  Be4O(CHO2)6. 
Propionate,  Be4O(C3H502)6. 
Isobutyrate  and  Butyrate,  Be4O(C4H702)e. 
Isovalerianate,  B 


BERYLLIUM.  21 

B.  Characteristics.  The  compounds  of  beryllium  closely 
resemble  those  of  aluminum.  The  oxide  is  white;  it  is  in- 
soluble in  water  and  unaffected  by  it.  The  hydroxide  is 
soluble  in  concentrated  solutions  of  its  own  salts  and  is 
precipitated  from  them  by  dilution.  It  is  also  soluble  in 
the  alkali  hydroxides  and  bicarbonates,  and  in  dilute  acids. 
The  halides  are  very  readily  hydrolyzed  by  water,  the  hy- 
drolysis in  the  case  of  the  chlorides,  bromides,  and  iodides 
being  practically  complete.  Normal  salts  of  the  non- volatile 
acids  only  can  be  crystallized  from  water;  of  these  the 
sulphate,  oxalate,  and  selenate  are  examples.  The  nitrate 
can  be  prepared  only  by  crystallization  from  strong  nitric  acid. 

The  double  alkali  tartrates  are  of  peculiar  interest,  both 
on  account  of  the  fact  that  beryllium  appears  to  replace 
not  only  the  positive  hydrogen  of  the  acid  but  also  in  part 
the  hydrogen  of  the  tartrate  ion,  and  also  because  the  pres- 
ence of  beryllium  in  the  salt  increases  the  molecular  rotation. 
This  influence  upon  the  molecular  rotation  is  shown  to  an 
even  greater  degree  in  the  case  of  the  malates  (Rosenheim 
and  Itsig).  Another  interesting  compound  is  the  basic 
acetate,  which,  although  almost  insoluble  in  water,  becomes 
soluble  after  hydrolysis  by  hot  or  cold  water.  It  is  soluble 
without  decomposition  in  glacial  acetic  acid,  methyl,  ethyl, 
andamyl  alcohols,  chloroform,  turpentine, ether  acetone, car- 
bon disulphide,  and  some  other  organic  solvents.  It  is  un- 
affected by  dry  air,  melts  at  283°-284°  C.,  boils  at  33o°-33i° 
C.,  and  may  be  sublimed.  It  was  used  by  Parsons  in  deter- 
mining the  atomic  weight  of  beryllium.  It  is  best  prepared 
by  the  action  of  glacial  acetic  acid  upon  the  dry  carbonate 
or  hydroxide. 

The  arc  spectrum  of  beryllium  is  characterized  by  lines 
in  the  blue  and  indigo. 

Estimation.  Beryllium  is  ordinarily  estimated  as  the 
oxide,  (BeO),  which  is  obtained  by  the  ignition  of  the  pre- 
cipitated hydroxide. 


22  THE  RARER   ELEMENTS. 

Separation.  Beryllium  closely  resembles  aluminum  in 
many  reactions.  It  may  be  separated  from  aluminum  (r) 
by  the  action  of  a  saturated  solution  of  acid  sodium  carbonate 
upon  the  hydroxides  of  iron,  aluminum  and  beryllium,  beryl- 
lium hydroxide  being  dissolved  (Parsons  and  Barnes) ;  (2) 
by  saturation  of  a  solution  of  the  two  chlorides  with  hydro- 
chloric acid  gas  in  the  presence  of  ether,  the  beryllium  re- 
maining in  solution,  while  the  aluminum  chloride  is  precipi- 
tated (Gooch  and  Havens,  Amer.  Jour.  Sci.  [4]  n,  416); 
(3)  by  the  action  of  hot  glacial  acetic  acid  upon  the  acetates, 
basic  beryllium  acetate  separating  out  on  cooling  (Parsons 
and  Robinson). 

EXPERIMENTAL  WORK  ON  BERYLLIUM. 

Experiment  i.  Extraction  of  beryllium  salts  from  beryl 
(BesA^SieOis).  Fuse  in  a  nickel  or  iron  crucible  10  grm.  of 
finely  powdered  mineral  with  10  grm.  of  potassium  hydrox- 
ide, and  cool.  Pulverize  the  fused  mass,  add  water  enough  to 
cover  it,  and  strong  sulphuric  acid  in  slight  excess.  Heat 
the  gelatinous  mass  until  fumes  of  sulphuric  acid  are  given 
off  and  the  residue  has  the  appearance  of  a  fine  white 
powder.  Extract  thoroughly  with  hot  water,  discarding  the 
insoluble  material.  Evaporate  until  the  alums  begin  to 
crystallize  from  the  solution,  and  allow  to  stand,  when  the 
greater  part  of  the  aluminum  will  separate  as  the  alum. 
Treat  the  mother  liquor  from  the  alum  with  nitric  acid,  to 
convert  all  iron  present  to  the  ferric  condition,  neutralize 
with  ammonium  hydroxide,  and  add  sodium  acid  carbonate 
in  crystals  to  saturation,  warming  gently  (50°  C.),  with  fre- 
quent stirring  for  about  an  hour;  or,  if  the  quantity  of  hy- 
droxide is  small,  bring  rapidly  to  boiling  and  boil  for  one 
minute  only.  Filter,  add  a  little  ammonium  sulphide  to 
remove  any  iron  in  solution,  and  dilute  with  about  five  or 
ten  volumes  of  water.  Pass  steam  through  the  liquid,  or 


EXPERIMENTAL   WORK   ON  BERYLLIUM.  23 

boil  if  the  amount  of  beryllium  is  small,  to  precipitate  the 
basic  carbonate  of  beryllium  (Parsons). 

Experiment  2.  Precipitation  of  beryllium  hydroxide 
(Be(OH)2).  (a)  To  a  solution  of  a  beryllium  salt  add  am- 
monium hydroxide,  and  note  the  insolubility  of  the  precipi- 
tate in  excess  of  that  reagent. 

(6)  To  another  portion  of  the  beryllium  solution  add 
a  solution  of  potassium  or  sodium  hydroxide,  and  note 
the  solvent  action  of  an  excess. 

(c)  Dilute  with  water  a  portion  of  the  alkaline  solution 
obtained  in  (b)  and  boil.     Note  the  reprecipitation  of  the 
hydroxide. 

(d)  To  another  portion  of  the  alkaline  solution  obtained 
in  (b)  add  ammonium  chloride,  and  boil. 

(e)  To  a  solution   of  a  beryllium  salt   add   ammonium 
sulphide. 

Experiment  3 .  Precipitation-  of  basic  beryllium  carbonate 
(#BeCO3/yBe(OH)2).  (a)  To  a  solution  of  a  beryllium  salt 
add  sodium  or  potassium  carbonate  in  solution.  Note  the 
solvent  action  of  an  excess  and  the  reprecipitation  on  boil- 
ing. 

(b)  Make  a  similar  experiment,  using  ammonium  car- 
bonate. 

Experiment  4.  Precipitation  of  beryllium  phosphate 
(Be3  (PO4)  2) .  To  a  solution  of  a  beryllium  salt  add  a  solution 
of  sodium  phosphate. 

Experiment  5.  Preparation  of  beryllium  basic  acetate 
(Be4O(C2H3O2)6).  Dissolve  some  beryllium  hydroxide  or 
carbonate  in  acetic  acid  and  evaporate  to  dryness.  Dis- 
solve the  dry  residue  in  excess  of  hot  glacial  acetic  acid  and 
allow  the  solution  to  cool. 

Experiment  6.  Action  of  sodium  acid  carbonate  upon 
beryllium  hydroxide.  To  a  small  amount  of  washed  beryl- 
lium hydroxide  add  2-3  grm.  of  solid  sodium  acid  carbonate 
and  20  cm.3  of  water,  and  heat  rapidly  to  boiling.  Note  the 


24  THE  RARER  ELEMENTS. 

solubility  of  the  hydroxide.     Dilute  to  200  cm.3  and  boil. 
Note  the  precipitation  of  the  hydroxide. 

Experiment  7.  Negative  tests  of  beryllium  salts.  Try 
the  action  of  hydrogen  sulphide  and  ammonium  oxalate 
upon  separate  portions  of  a  solution  of  a  beryllium  salt. 
Add  sodium  acetate  to  a  solution  of  a  beryllium  salt  and 
boil.  Note  the  absence  of  precipitation  in  each  case. 


CHAPTER   III. 
THE  RADIO  ELEMENTS  * 

THE  property  of  matter  known  as  radioactivity  was  dis- 
covered in  1896  by  M.  Henri  Becquerel,  who  observed  that 
the  salts  of  uranium  emitted  a  characteristic  radiation 
which  was  capable  of  producing  an  effect  on  a  photographic 
plate  through  several  thicknesses  of  black  paper  wholly 
opaque  to  ordinary  light. 

The  radiation  emitted  by  radioactive  substances  has 
been  shown  to  be  complex  in  character  and  to  include  three 
distinctive  types  known  as  the  a,  /?  and  f  radiations. 

The  a  radiation  consists  of  positively  electrified  particles 
of  a  mass  comparable  with  that  of  an  atom  of  helium  and 
moving  with  a  velocity  equal  to  about  1-15  of  the  velocity 
of  light.  The  a  rays  are  completely  stopped  by  thin  layers 
of  ordinary  matter  and  are  deflected  by  magnetic  and 
electrostatic  fields. 

The  /?  radiation  consists  of  negatively  electrified  par- 
ticles having  a  mass  which  is  probably  not  greater  than 
one-thousandth  that  of  a  hydrogen  atom  and  projected  at 
a  velocity  which  in  some  cases  is  as  high  as  nine-tenths  the 
velocity  of  light.  The  /?  rays  have  a  greater  power  for 
penetrating  matter  than  the  a  rays,  but  are  more  readily 
deflected  than  the  latter  by  both  magnetic  and  electrostatic 
fields. 

The  r  radiation  is  believed  to  consist  of  ether  pulses 

*  This  chapter  was  contributed  by  Bertram  B.  Boltwcod,  Ph.D.,  of  Yale  Uni- 
versity. 


26  THE   RARER  ELEMENTS. 

travelling  with  the  velocity  of  light,  and  is  analogous  in  many 
respects  to  the  Roentgen  or  X  radiation.  The  7-  rays  have 
a  high  penetrative  power  and  are  not  affected  by  either 
electrostatic  or  magnetic  fields. 

All  three  types  of  radiation  are  capable  of  producing 
charged  carriers  of  electricity,  known  as  ions,  in  the  gases 
which  they  traverse,  and  in  this  manner  render  the  gases 
conductive  to  electricity.  They  also  excite  phosphores- 
cence in  various  chemical  compounds  and  produce  an  effect 
on  photographic  plates. 

The  chemical  elements  which  exhibit  the  phenomena  of 
radioactivity  are  termed  radioelements.  In  order  to  explain 
their  behavior,  a  theory,  known  as  the  disintegration  theory, 
has  been  proposed  by  Rutherford  and  Soddy  and  has  now 
been  generally  accepted.  In  this  theory  it  is  assumed  that 
the  radioelements  represent  unstable  forms  of  matter  the 
atoms  of  which  are  spontaneously  undergoing  changes  which 
result  in  the  production  of  new  forms  of  matter  having  dif- 
ferent physical  and  chemical  properties.  These  changes  are 
accompanied  by  the  emission  of  energy  usually  appearing  in 
the  form  of  heat  derived  from  the  internal  energy  of  the 
atoms  in  process  of  transformation.  The  disintegration  of 
the  radioelements  takes  place  according  to  a  simple  ex- 
ponential law  which  is  given  by  the  expression  N  =  N0£~^ 
where  NO  is  the  number  of  atoms  of  the  element  present  at 
the  start,  N  is  the  number  remaining  unchanged  after  any 
time  /,  e  is  the  base  of  the  natural  system  of  logarithms  and 
X  is  the  constant  of  change  of  the  given  element.  The  con- 
stant of  change  is  a  definite  and  characteristic  quantity  for 
any  particular  radioelement  and  its  value  is  unaffected  by 
any  of  the  extremes  of  temperature  and  pressure  to  which  it 
has  been  possible  to  subject  radioactive  substances.  The 
constant  of  change  represents  the  fraction  of  any  given 
quantity  of  the  radioelement  which  undergoes  transforma- 
tion in  the  unit  of  time. 


THE  RADIO  ELEMENTS.  27 

The  disintegration  of  the  radioelements  is  wholly  inde- 
pendent of  the  chemical  state  or  form  of  combination  of  the 
radioelements,  and  proceeds  at  a  constant  rate  which  is  the 
same  in  all  compounds  of  the  same  element.  As  a  necessary 
consequence  of  this  fact  the  relative  radioactivity  of  different 
chemical  compounds  of  the  same  radioelement  is  directly 
proportional  to  the  relative  quantities  of  the  element  which 
they  each  contain. 

The  instability  of  atomic  structure  may  continue  through 
a  considerable  number  of  successive  changes  until  a  final 
stable  form  of  matter  is  reached.  A  radioelement  from 
which  any  other  radioelement  is  formed  is  called  the  "par- 
ent" of  the  latter  and  the  element  formed  is  known  as  the 
"product"  of  the  parent  from  which  it  is  produced. 

The  known  radioelements  can  be  divided  into  two  general 
groups:  the  uranium  series  and  the  thorium  series.  The 
uranium  series  comprises  uranium  and  seventeen  products  of 
uranium,  including  ionium,  radium,  actinium  and  polonium. 
The  thorium  series  contains  eight  members  in  addition  to 
thorium  itself.  The  chemical  behavior  of  the  radioelements, 
with  the  exception  of  uranium  and  thorium,  has  not  been 
very  thoroughly  investigated,  but  there  is  every  reason  for 
believing  that  they  all  possess  distinct  and  characteristic 
chemical  properties. 

URANIUM,  U,  238.5. 

The  general  properties  of  uranium  will  be  discussed  on 
page  139.  It  is  one  of  the  most  slowly  changing  of  the 
radioelements,  its  rate  of  disintegration  corresponding  to 
the  transformation  in  one  year  of  about  one  ten-billionth  of 
the  total  amount  of  uranium  present.  The  time  required 
for  exactly  one-half  of  any  given  quantity  of  uranium  to  dis- 
integrate completely  into  other  forms  of  matter  is  about  six 
billion  year?.  Uranium  when  completely  freed  from  its  dis- 


\  -v 

OF  THE 


OF 


28  THE  R4RER  ELEMENTS. 

integration  products  emits  only  a  rays,  but  unless  freshly 
prepared  its  compounds  contain  uranium  X,  which  is  the 
source  of  both  a  /?  and  a  7-  radiation.  Uranium  salts  can 
be  obtained  free  from  uranium  X  by  recrystallization,  the 
uranium  X  remaining  in  the  mother  liquor. 

Uranium  X.  Uranium  X  is  the  first  disintegration  prod- 
uct of  uranium  and  is  gradually  formed  in  uranium  salts 
on  standing.  The  amount  which  accumulates  reached  a 
maximum  after  about  150  days,  when  a  state  of  radioactive 
equilibrium  is  reached  and  the  amount  of  uranium  X  which 
is  produced  in  any  subsequent  time  is  exactly  equal  to  the 
amount  which  disintegrates  in  the  same  period.  Uranium 
X  was  first  discovered  by  Crookes  in  1900.  It  emits  /?  and 
f  rays,  and  in  22  days  one-half  of  any  given  quantity  of  it 
is  transformed  into  other  substances.  It  can  be  obtained 
free  from  uranium  by  treating  pure  uranium  nitrate,  dried 
at  1 1 8°,  with  ordinary  ether.  The  uranium  nitrate  is  dis- 
solved by  the  ether,  leaving  a  slight  residue  which  contains 
the  greater  part  of  the  uranium  X. 

IONIUM,  lo. 

Ionium  is  a  radioelement  intermediate  between  uranium, 
of  which  it  is  a  product,  and  radium,  of  which  it  is  the 
parent.  It  was  discovered  by  Boltwood  in  1907.  It  has 
not  been  obtained  in  sufficient  quantity  to  permit  a  determi- 
nation of  its  atomic  weight  or  of  its  spectrum.  From  theo- 
retical considerations  its  atomic  weight  is  probably  about 
230.  From  uranium  minerals  containing  thorium  the  ioni- 
um is  separated  with  the  thorium,  to  which  it  shows  a  strik- 
ing similarity  in  chemical  behavior.  The  constant  of  change 
of  ionium  has  not  yet  been  determined,  but  its  rate  of 
transformation  is  very  possibly  as  slow  as  that  of  radium. 


THE  RADIO  ELEMENTS.  29 

RADIUM,  Ra,  226.5. 

Discovery.  Radium  was  discovered  in  1898  by  P.  and 
S.  Curie  and  G.  Bemont.  In  the  course  of  an  investigation 
of  the  relative  radioactivity  of  certain  uranium  salts  and 
uranium  minerals  it  was  noted  by  Mme.  Curie  that  although 
the  activity  of  the  uranium  salts  was  quite  closely  pro- 
portional to  the  amounts  of  uranium  contained  in  them,  the 
activity  of  the  uranium  minerals  was  much  greater  than  was 
to  be  expected  from  the  uranium  which  they  contained. 
This  suggested  that  there  might  be  present  in  the  minerals 
some  other  more  strongly  radioactive  constituent,  and  a 
further  investigation  led  to  the  isolation  of  a  highly  radio- 
active substance  resembling  barium  in  its  chemical  proper- 
ties. 

Occurrence.  Radium  has  been  found  widely  distributed 
in  minute  proportions  in  many  rocks  and  minerals,  in  sea 
water  and  in  the  waters  of  certain  mineral  springs.  The 
chief  source  of  radium  has  been  the  minerals  containing  a 
high  proportion  of  uranium,  principally  pitchblende,  and 
the  present  supply  has  been  almost  entirely  obtained  from 
the  insoluble  residues  remaining  after  the  treatment  of 
pitchblende  for  the  commercial  extraction  of  uranium. 

Extraction.  The  pitchblende  residues  consist  chiefly  of 
the  sulphates  of  lead  and  calcium,  together  with  the  oxides 
of  silicon,  aluminum  and  iron.  They  also  contain  greater 
or  less  quantities  of  nearly  all  the  metals  (copper,  bismuth, 
zinc,  cobalt,  manganese,  nickel,  vanadium,  antimony, 
thallium,  the  rare  earths,  niobium,  tantalum,  arsenic, 
barium,  etc.).  They  are  first  treated  with  boiling,  concen- 
trated sodium  hydroxide  solution,  washed  with  water,  and 
digested  with  hydrochloric  acid.  Much  of  the  material  is 
removed  in  this  operation,  the  radium  remaining  in  the  un- 
dissolved  portion.  After  further  washing,  the  residue  is 
boiled  with  a  concentrated  sodium  carbonate  solution  which 


30  THE  R4RER  ELEMENTS. 

converts  the  alkali-earths  into  carbonates.  The  residue  is 
again  washed  to  remove  all  traces  of  sulphates,  and  is  then 
treated  with  hydrochloric  acid,  which  dissolves  the  barium 
and  radium  together  with  certain  of  the  other  constituents. 
The  solution  of  the  chlorides  is  further  purified  until  a  salt 
containing  only  barium  and  radium  is  obtained.  The  mixed 
chlorides  of  barium  and  radium  are  subjected  to  a  long 
series  of  fractional  recrystallizations,  the  radium  being  con- 
centrated in  the  least  soluble  portion  of  the  fractions.  In 
this  manner  a  pure  chloride  of  radium  is  ultimately  obtained. 
The  concentration  of  the  radium  proceeds  more  rapidly  if 
the  recrystallization  is  conducted  with  the  double  bromide. 

The  Element.  Radium  has  not  yet  been  obtained  in 
elementary  form. 

Compounds.  A.  Typical  forms.  The  following  com- 
pounds of  radium  have  been  described : 

Hydroxide,  Ra(OH)2.       Chloride,  RaCl2;  RaCl2.2H20. 
Carbonate,  RaCO3.  Bromide,  RaBr2;  RaBr2.2H2O. 

Nitrate,  Ra(NO3)2. 

B.  Characteristics.  The  exceeding  rarity  of  the  com- 
pounds of  radium  has  rendered  impossible  any  extensive 
study  of  their  chemical  characteristics.  Their  behavior, 
however,  is  very  similar  to  that  of  the  barium  compounds. 
The  chloride  is  described  as  a  grayish-white  powder,  less 
soluble  in  water  and  in  dilute  hydrochloric  acid  than  is 
the  chloride  of  barium.  The  bromide  gives  off  bromine  in 
the  air,  and  becomes  alkaline  because  of  the  formation  of 
the  hydroxide.  The  hydroxide  absorbs  carbon  dioxide  and 
becomes  the  carbonate,  which  is  insoluble.  Salts  of  radium 
color  the  flame  carmine. 

Certain  physiological  effects  of  radium  compounds  are 
of  interest.  By  exposure  to  radium  rays  the  skin  is  burned, 
bacteria  are  destroyed  or  hindered  in  development,  plants 
lose  their  chlorophyl,  and  seeds  their  power  of  germination. 


THE  RADIO  ELEMENTS.  31 

Radium  is  a  disintegration  product  of  uranium,  and  is 
formed  directly  from  ionium.  It  is  found  in  all  uranium 
minerals,  and  the  amount  present  is  directly  proportional 
to  the  amount  of  uranium  in  the  mineral,  one  part  of  radium 
being  associated  with  approximately  three  million  parts  of 
uranium.  Radium  salts  have  been  found  to  emit  heat  at  a 
rate  corresponding  to  about  100  gram  calories  per  hour  per 
gram  of  radium,  and  are  thus  able  to  maintain  their  tempera- 
ture considerably  above  that  of  their  surroundings. 

Pure  radium,  free  from  its  disintegration  products,  gives 
out  only  a  rays,  but  owing  to  the  presence  of  these  products, 
ordinary  radium  salts  emit  all  three  types  of  radiation.  The 
rate  of  disintegration  of  radium  corresponds  to  the  trans- 
formation of  about  thirty-five  one-hundred-thousandths  of 
its  mass  per  year,  and  the  time  required  for  exactly  half  of 
any  given  quantity  to  completely  disintegrate  into  other 
elements  is  about  2000  years.  One  of  the  non-radioactive 
products  of  the  disintegration  of  radium  is  the  rare  gas 
helium,  which  is  very  probably  formed  from  the  expelled 
a  particles,  and  there  ar®  many  reasons  for  supposing  that 
the  final,  stable  form  of  matter  ultimately  attained  after  the 
series  of  radioactive  changes  is  ordinary  lead. 

Radium  Products.  Eight  successive  radioactive  dis- 
integration products  of  radium  have  been  identified.  The 
first  product  formed  is  a  gaseous  element  known  as  the 
emanation,  which  is  incapable  of  entering  into  chemical 
combination,  and  in  this  respect  is  similar  to  argon  and 
helium.  It  disintegrates  rather  rapidly,  forming  solid, 
active  products  which  are  deposited  on  the  walls  of  a  vessel 
containing  the  emanation,  or  on  the  surface  of  any  object 
with  which  it  is  in  contact,  in  this  manner  giving  rise  to  the 
phenomenon  known  as  ''induced"  or  "excited"  activity. 
The  emanation  is  condensed  at  the  temperature  of  liquid 
air  and  converted  into  a  gas  again  on  warming.  The  emana- 
tion has  been  found  to  give  a  characteristic  bright  line 


32  THE  RARER  ELEMENTS. 

spectrum,  and  its  density  has  been  shown  to  correspond  to 
an  atomic  weight  not  very  different  from  that  of  radium. 

The  products  of  radium  emanation,  taken  in  their  order 
of  production,  are  known  as  radium  A,  B,  C,  D,  E,  F  and  G. 
Radium  D  is  commonly  called  "radio-lead,"  from  the  fact 
that  it  is  separated  with  the  lead  from  uranium  minerals 
and  shows  a  close  similarity  to  lead  in  its  chemical  behavior. 
Radium  G  is  better  known  as  polonium.  It  was  the  first 
of  the  strongly  radioactive  substances  to  be  identified,  and 
was  discovered  in  1898  by  P.  and  S.  Curie.  It  emits  only  a 
rays  and  is  half  transformed  in  a  period  of  143  days.  It  has 
not  been  obtained  pure  in  sufficient  quantity  to  make  a 
determination  of  its  spectrum  or  atomic  weight  possible. 
It  is  separated  with  the  bismuth  from  uranium  minerals 
and  exhibits  a  chemical  behavior  similar  to  that  of  both 
bismuth  and  tellurium. 

ACTINIUM,  Ac. 

The  radioelement  known  as  actinium  was  separated  from 
uranium  minerals  by  Debierne  in  1899.  It  has  not  yet  been 
possible  to  determine  either  its  spectrum  or  its  atomic 
weight.  Its  rate  of  transformation  is  also  unknown,  but  it 
is  probably  very  slow,  since  actinium  preparations  retain 
their  activity  unimpaired  for  considerable  periods.  Actin- 
ium is  apparently  a  disintegration  product  of  uranium 
and  occurs  in  exceedingly  small  proportions  in  all  uranium 
minerals.  It  is  separated  with  the  rare  earths  and  is  finally 
obtained  associated  with  the  lanthanum. 

Actinium  Products.  Five  successive  radioactive  prod- 
ucts of  the  disintegration  of  actinium  have  been  identified. 
These  taken  in  their  order  are  radioactinium,  actinium  X, 
actinium  emanation,  actinium  A,  and  actinium  B.  But  little 
is  known  concerning  the  chemistry  of  these  products. 
Actinium  emanation  is  a  gas,  apparently  inert  like  the 


THE   RADIO  ELEMENTS.  33 

radium  emanation,  and  similarly  condensed  at  the  tempera- 
ture of  liquid  air. 

THORIUM,  Th,  232.5. 

The  radioactivity  of  thorium  was  independently  dis- 
covered by  C.  G.  Schmidt  and  Mme.  Curie  in  1898.  The  rate 
of  transformation  of  thorium  has  not  yet  been  definitely 
determined,  but  is  undoubtedly  much  slower  even  than  that 
of  uranium.  According  to  Hahn  the  disintegration  of 
thorium  is  accompanied  by  the  expulsion  of  a  particles,  but 
ordinary  thorium  salts  containing  disintegration  products 
of  thorium  emit  all  three  types  of  radiation. 

Thorium  Products.  Eight  successive  radioactive  disin- 
tegration products  of  thorium  have  been  identified.  These, 
taken  in  the  order  of  their  production,  are  known  as  meso- 
thorium  i,  mesothorium  2,  radiothorium,  thorium  X,  eman- 
ation, thorium  A,  thorium  B,  and  thorium  C.  Mesothorium 
i  and  thorium  X  appear  to  have  chemical  properties  similar 
to  barium,  while  radiothorium  resembles  thorium  so  closely 
in  its  chemical  behavior  that  a  direct,  chemical  separation 
of  these  two  elements  has  not  yet  been  effected.  The 
thorium  emanation,  like  the  other  emanations,  exhibits  the 
characteristics  of  an  inert  gas  of  the  argon  family,  and  is 
condensed  at  the  temperature  of  liquid  air.  Very  little  is 
known  concerning  the  chemical  properties  of  the  other  mem- 
bers of  this  series. 

References:  Radio- Activity,  by  E.  Rutherford  (second  edition),  Cambridge 
University  Press,  1905;  Radioactive  Transformations,  by  E.  Rutherford,  Charles 
Scribner's  Sons,  New  York,  1906;  Die  Radioaktivitat,  by  W,  Marckwald,  Ber.  d. 
chem.  Ges.,  xxxxi,  1524,  1908. 


34 


'I  HE  RARER   ELEMENTS. 


TABLE  OF  RADIOACTIVE  ELEMENTS. 

SHOWING  THE  TYPE  OF  RADIATION  EMITTED  BY  EACH  ELEMENT,  ITS  CONSTANT 
or  CHANGE,  AND  THE  TIME  REQUIRED  FOR  ONE-HALF  OF  ANY  GIVEN 
QUANTITY  TO  DISINTEGRATE  INTO  OTHER  FORMS  OF  MATTER.  (According 
to  Rutherford.) 


Name. 

Radiation 
emitted. 

Disintegration  Con- 
stant. 

Half-value  Period. 

Uranium 

ct 

i  i6Xio"10  (year)"1 

Uranium.  X 

B  r 

7  icXio"  2  (dav^""1 

Ionium  .               ..... 

a  (8  r?) 

? 

p 

Radium.              ........ 

at 

3  «;  X  io~~4  (year)"1 

Radium  emanation 

i  8  X  iQ"1  (day)"1 

Radium  A 

a 

3  8cX  io~3  (sec  }~l 

Radium  B  .    . 

B 

A  A.  X  io~4  (sec  }~l 

Radium  C    .  . 

r 

a  B  r 

6  i   X  io~4  (sec  )~x 

Radium  D..    .....    . 

no  rays 

? 

f  40  years  (?) 

no  rays 

i  15X10"'  (day)"1 

\  1  2  years  (?) 

Radium  F      

R 

i  44  X  lo"1  (day)"1 

4  8  days 

Radium  G  \ 

a 

4.8  Xio-*  (day)"1 

Polonium    / 
Actinium 

no  rays 

? 

P 

Radioaccmium       ...... 

CL 

3.5   Xio~2  (day)"1 

IQ  e  days 

Actinium  X   ..... 

a 

6.8   Xio-2  (day)"1 

10.2  days. 

Actinium  emanation  .... 

a 

no  rays 

1.8   Xio-1  (sec.)"1 
3.2   Xio"4  (sec.)"1 

3.9  seconds, 
36  minutes. 

Actinium  B 

a,  8  r 

<;  4  X  io~3  (sec  )-1 

2.1  minutes. 

(X 

•? 

? 

M^esothorium  i 

no  rays 

i  2  X  lo"1  (year)"1 

z.z  years. 

M^esothorium  2  .       ..... 

B 

3.1   X  io~5  (sec  )-1 

6.2  hours. 

Radiothorium    ..  ...... 

a 

0.4  X  io~4  Tdav)~ 

77,7  days. 

Thorium  X                

a 

2.2  X  io~8  (sec  )~ 

3.6  days. 

Thorium  emanation  

a 
P 

1.3  Xio-'4  (sec.)~ 
1.8  Xio"5  (sec.)" 

54  seconds. 
10.6  hours. 

Thorium  B  

a 

2.2  X  io~  *  (sec.)— 

55  minutes. 

Thorium  C               

a,  9,  r 

? 

a  few  seconds. 

CHAPTER   IV. 
THE  RARE  EARTHS*. 

The  rare  earth  elements  may  conveniently  be  classified 
as  follows:! 

I.  THE  YTTRIUM  GROUP,  consisting  of 

1.  Yttrium.  6.  Ytterbium. 

2.  Erbium.  (Neoytterbium.) 

3.  Holmium.  (Lutecium.) 

4.  Thulium.  7.  Europium,  t 

5.  Dysprosium.  8.  Victorium.t 
II.  THE  TERBIUM  GROUP,  consisting  of 

i.  Terbium. §  2.  Gadolinium.!! 

III.  THE  CERIUM  GROUP,  consisting  of 

1.  Cerium.  5.  Samarium. 

2.  Lanthanum.  6.  Scandium. 

3.  Neodymium.  7.  Decipium.{ 

4.  Praseodymium. 

IV.  THORIUM. 
V.  ZIRCONIUM. 

The  rare  earths  occur  so  closely  associated  that  it  will  be 
advantageous  to  consider  their  occurrence  and  their  separa- 
tion before  taking  them  up  separately. 

Occurrence.^ — Mineral  sources  of  the  rare  earths  are  as 
follows : 

*  The  term  earth  is  applied  to  certain  metallic  oxides  which  were  formerly  re- 
garded as  elementary  bodies,  as  Y2O3,  Er2O3,  La2O3,  etc.,  and  names  ending  in  a 
are  often  used  in  designating  them,  as  yttria,  erbia,  etc.  The  ending  um  designates 
the  element,  as  yttrium,  erbium,  lanthanum. 

f  According  to  Bohm. 

J  Classification  still  doubtful. 

§  Placed  by  some  in  yttrium  group. 

||  Placed  by  some  in  cerium  group. 

1  See  also  Schilling,  Das  Vorkommen  der  seltenen  Erden,  R.  Oldenbourg, 
Munchen,  1904. 

35 


36 


THE  R4RER   ELEMENTS. 


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THE  R/IRER   ELEMENTS. 


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THE  RARER    ELEMENTS. 


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Edwarsite,  vid.  Monazite  . 

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Hussakite,  vid.  Xenotime. 
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Scovillite,  vid.  Rhabdopha 
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Lanthanite  

THE  RARER  ELEMENTS. 


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THE  RARE  EARTHS.  43 

Separation.  The  methods  of  separation  here  enumer- 
ated, with  the  exception  of  the  last  three,  are  described  in 
full  in  Bohm's  * '  Darstellung  der  seltenen  Erden,"  volume  i, 
pages  1 08  to  490. 

(1)  Ignition  of  the  nitrates,  carbonates,  or  oxalates,  and 

treatment  of  the  product  with  ammonium  nitrate, 
ammonium  chloride,  or  dilute  acid. 

(2)  Treatment  of  suspended  hydroxides  with  chlorine. 

(3)  Oxidation  with  potassium  permanganate. 

(4)  Treatment  with  peroxides,  as  PbO2,  etc. 

(5)  Oxidation  with  hydrogen  dioxide  or  sodium  dioxide. 

(6)  Treatment  with  persulphates. 

(7)  Treatment  with  the  electric  current. 

(8)  Formation  of  basic  nitrates. 

(a)  By  treating  the  nitrates  with  oxides. 

(b)  By  treating  the  neutral  nitrates  with  hot  water. 

(9)  Formation  of  basic  chlorides. 

(a)  By  treating  the  chlorides  with  water. 

(b)  By  treating  the  chlorides  with  magnesium  oxide 

or  copper  oxide. 

(10)  Formation  of  basic  sulphates  by  the  action  of  water, 
(n)  Fractional  precipitation  with  ammonium  hydroxide. 

(12)  Fractional   precipitation   with   sodium   or  potassium 

hydroxide. 

(13)  Partial  precipitation  with  anilin. 

(14)  Precipitation  by  alkali  hyponitrides. 

(15)  Precipitation  by  sulphurous  acid  and  sulphites. 

(16)  Precipitation  by  sodium  thiosulphate. 

(17)  Precipitation  by  carbonates. 

(18)  Precipitation  as  chromates. 

(19)  Precipitation  by  formates. 

(20)  Precipitation  by  acetates. 

(21)  Action  of  dilute  acid  upon  the  oxalates. 

(22)  Precipitation  as  the  sulphates. 

(23)  Fractional  crystallization  'of  the  nitrates. 


44  THE   RARER   ELEMENTS. 

(24)  Action  of  alcohol  upon  the  nitrates. 

(25)  Action  of  (a)  acetylacetone,  (6)  ethylsulphate,  (c)  salts 

of  sulphanilic  acid. 

(26)  Fractional  crystallization  of  the  double  salts: 

(a)  Double  sulphates  with  alkali  sulphates. 

(b)  Double  nitrates  with  ammonium  nitrate. 

(c)  Double  nitrates  with  magnesium  nitrate. 

(d)  Double  nitrates  with  bismuth  nitrate. 

(e)  Double  fluorides  with  alkali  and  magnesium  fluo- 

rides. 

(27)  Action  of  (a)  neutral  or  acid  potassium  oxalate;  (b) 

ammonium  oxalate. 

(28)  Fractional   crystallization   of   the   bromates    (James, 

Jour.  Amer.  Chem.  Soc.  xxx,  182). 

(29)  Fractional   precipitation  of  the   succinates    (Lenher, 

Jour.  Amer.  Chem.  Soc.  xxx,  572.) 

(30)  Action  of   ammonium  carbonate  upon  the  oxalates 

(James,  Jour.  Amer.  Chem.  Soc.  xxix,  495). 
The  separation  of  the  rare  earths  cannot  be  made  with 
quantitative  accuracy.  For  a  working  scheme,  however, 
the  student  is  referred  to  a  method  worked  out  by  James 
(Jour.  Amer.  Chem.  Soc.  xxx,  979)  and  diagrammatically 
shown  on  the  following  page.  This  is  the  only  scheme  of 
separation  that  has  come  to  the  notice  of  the  author,  and  it 
is  followed  in  this  book  where  methods  are  described  at  all 
in  detail.  It  may  be  added  that  Urbain  (Jour.  chim.  phys. 
iv,  31)  has  arranged  the  rare  earths  according  to  their 
solubilities  as  follows:  lanthanum,  cerium,  praseodymium, 
neodymium,  samarium,  europium,  gadolinium,  terbium, 
dysprosium,  holmium,  yttrium,  erbium,  thulium,  ytterbium. 


THE  RARE  EARTHS. 


46  THE  RARER  ELEMENTS. 

I.  THE  YTTRIUM  GROUP, 
i.  YTTRIUM,  Y,  89. 

Discovery.  In  the  year  1794,  Gadolin  (Kongl.  Vet. 
Acad.  Handl.  xv,  137;  Crell  Annal.  (1796)  i,  313)  discovered 
a  new  earth  in  a  mineral  later  called  Gadolinite,  which  had 
been  discovered  by  Arrhenius  and  described  by  Geyer  in 
1788  (Crell  Annal.  (1788)  i,  229).  In  1797  Eckeberg  con- 
firmed Gadolin's  discovery  and  named  the  new  earth  Yttria 
(Kong.  Vet.  Acad.  Handl.  xvm,  156;  Crell  Annal.  (1799) 
n,  63),  deriving  the  name  from  Ytterby,  the  source  of  the 
mineral. 

Occurrence.  Yttrium  occurs  always  in  combination. 
Its  chief  sources  are  the  minerals  gadolinite  and  xenotime, 
and  monazite  residues  (vid.  Occurrence  of  Rare  Earths,  page 

35)- 

Extraction.  The  following  are  common  methods  for  the 
extraction  of  yttrium  salts  from  minerals: 

(1)  From  gadolinite  (or  any  other  silicate).     The  finely 
powdered  mineral  is  mixed  with  common  sulphuric  acid  until 
the  mass  has  the  consistency  of  thick  paste.      It  is  then 
heated  until  dry  and  hard,  pulverized,  and  extracted  with 
cold  water.     From  this  extraction  the  oxalates  are  precipi- 
tated by  the  addition  of  oxalic  acid ;  they  are  then  washed, 
dried,  and  heated  at  400°  C.     The  oxides  thus  obtained  are 
dissolved  in  sulphuric  acid,  and  the  solution  is  saturated  with 
potassium  or  sodium  sulphate.     The  double  sulphates  of 
the  cerium  group  are  precipitated,  and  the  members  of  the 
yttrium  group  remain  in  solution. 

(2)  From  gadolinite.     The   mineral  is  decomposed  by 
aqua  regia  (vid.  Experiment  i). 

(3)  From  samarskite.     The  mineral  is  decomposed  by 
hydrofluoric  acid.     The  niobic  and  tantalic  acids  go  into 


YTTRIUM.  47 

solution,  and  the  yttrium  earths,  together  with  uranium 
oxide,     remain     (Lawrence    Smith,    Amer.    Chem.    Jour. 

v,  44)- 

The  Element.  A.  Preparation.  Elementary  yttrium 
may  be  obtained  (i)  by  heating  the  chloride  with  potas- 
sium (Berzelius) ;  (2)  by  subjecting  the  melted  double 
chloride  of  sodium  and  yttrium  to  electrolysis  (Cleve,  Bull. 
Soc.  Chim.  d.  Paris  [2]  xvm,  193);  (3)  by  heating  the 
oxide  with  magnesium  (Winkler,  Ber.  Dtsch.  chem.  Ges. 
xxm,  787). 

B.  Properties.  Yttrium  is  a  grayish-black  powder, 
which  decomposes  water  only  slightly  at  ordinary  tempera- 
tures, but  more  rapidly  on  boiling,  forming  the  oxide. 
Ignited  on  platinum  in  the  air,  it  burns  to  the  oxide  with  a 
brilliant  light ;  in  oxygen  with  a  very  intense  glow.  It  is 
very  soluble  in  dilute  acids,  including  acetic,  but  is  only 
slightly  soluble  in  concentrated  sulphuric  acid.  It  decom- 
poses potassium  hydroxide  at  the  boiling  temperature. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  yttrium: 

Oxide,  Y2O3. 
Hydroxide,  Y(OH)3. 

Carbonates,  Y2(CO3)3  +  3H2O ;         Y2(CO3)3  -  Na2CO3  +  4H2O ; 
Y2(C03)3-(NH4)2C03  +  2H20. 

Chlorides,    YC13;        YC13  +  6H2O;         YCl3.3HgCl2  +  9H2O; 
YC13  •  2AuCl3  +  i6H2O ;  2  YC1S-  3PtCl2+  24H2O. 

Chlorate,  Y(C1O3)3  +  8H2O. 
Perchlorate,  Y(C1O4)3  +  8H2O. 
Bromides,  YBr3 ;  YBr3  +  9H2O. 
Bromate,  Y(BrO3)3  +  9H20. 
Iodide,  YI3. 

lodate,  Y(I03)3  +  3H20. 
Periodate,  Y2O3  •  I2O7  +  8H2O. 
Fluoride,  YF3  +  o.5H2O. 


48  THE  RARER  ELEMENTS 

Nitrates,  Y(NO3)8  +  6H2O;  2Y2O3-3N2O5 
Cyanides,  YKFe(CN)6  +  2H2O;  Y(SCN)3  +  6H2O. 
Sulphates,  Y2(S04)3  +  8H2O ;  Y2(SO4)3  -  4K2SO4 ; 

Y2(SO4)3.Na2S04+2H2O. 
Sulphite,  Y2(SO3)3  +  3H2O. 
Seleniates,  Y2(SeO4)3  +  8H2O ;         Y2(SeO4)3  •  K2SeO4  +  6H2O ; 

Y2(Se04)3-(NH4)2Se04  +  6H20. 
Selenites,  Y2(SeO3)3  +  1 2H2O ;  Y2O3  •  4SeO2  +  4H2O. 
Sulphide,  Y2S3. 
Oxalate,  Y2(C2O4)3  +  9H2O. 
Phosphates,  YPO4;  Y(PO3)3;  YHP2O7  +  3.5H2O. 
Chromate,  Y2(CrO4)3  •  K?CrO4  +  *H2O. 
Tungstate,  Y2(W04)3  +  6H2O. 
Carbide,  YC2. 

B.  Characteristics.  The  compounds  of  yttrium  have 
few  characteristic  reactions.  They  resemble  quite  closely 
the  compounds  of  aluminum,  but  yttrium  differs  from 
aluminum  in  having  a  hydroxide  insoluble  in  excess  of 
sodium  or  potassium  hydroxide  and  in  forming  no  alums. 
The  salts  of  yttrium  give  no  absorption  spectra.  Yttrium 
sulphate  differs  from  the  sulphate  of  cerium  in  forming 
no  insoluble  double  sulphate  with  potassium  or  sodium 
sulphate. 

Estimation.  Yttrium  is  generally  weighed  as  the  oxide, 
(Y2O3),  which  has  been  obtained  by  the  ignition  of  the 
hydroxide  or  the  oxalate. 

Separation.  In  the  course  of  analysis  the  yttrium, 
earths  are  precipitated  with  the  aluminum  group.  They 
may  be  separated  from  aluminum  by  precipitation  with 
oxalic  acid  or  ammonium  oxalate  in  faintly  acid  solution; 
in  this  reaction  they  resemble  the  other  members  of  the 
rare-earth  group  (Ce,  La,  Pr,  Nd,  Th,  Zr,  etc.).  They  may 
be  separated  from  these  by  saturating  a  solution  of  the  sul- 
phates with  potassium  sulphate;  the  yttrium  earths  do  not 


EXPERIMENTAL   WORK  ON    YTTRIUM.  49 

form  a  double  sulphate  insoluble  in  potassium  sulphate 
as  do  the  others. 

For  the  separation  of  yttrium  from  the  very  rare  mem- 
bers of  its  group  Methods  8,  9 (a),  n,  18,  21  and  28  (page  43) 
have  been  used.  James  recommends  the  fractional  crystal- 
lization of  the  bromates  (28),  and  finds  the  yttrium  in  the 
fraction  between  the  holmium  and  the  erbium.  Taking  the 
fractions  free  from  holmium,  he  converts  them  into  the 
neutral  nitrates.  These  nitrates  of  yttrium  and  erbium 
are  boiled  with  the  addition  of  magnesium  oxide  until  the 
liquid  shows  no  absorption  bands  of  erbium. 


EXPERIMENTAL  WORK  ON  YTTRIUM. 

Experiment  i.  Extraction  of  yttrium  salts  from  gado- 
linite  (Be2FeY2Si2O10).  Warm  5  grm.  of  finely  powdered 
mineral  with  aqua  regia  until  it  is  completely  decomposed. 
Evaporate  on  a  water-bath  and  desiccate  to  remove  the 
silica.  Extract  with  hot  water  and  a  little  hydrochloric 
acid,  and  add  to  the  extract  ammonium  oxalate  until 
precipitation  ceases.  Filter  off  the  precipitate,  which  con- 
sists of  the  oxalates  of  the  yttrium  and  cerium  groups,  to- 
gether with  traces  of  the  oxalates  of  manganese  and  cal- 
cium; dry  and  ignite.  Dissolve  in  a  small  amount  of 
hydrochloric  acid  the  oxides  thus  obtained,  and  saturate 
the  solution  with  potassium  sulphate;  this  precipitates 
the  members  of  the  cerium  group  as  the  double  sulphates. 
Filter,  and  wash  with  a  solution  of  potassium  sulphate. 
From  the  filtrate  precipitate  the  yttrium  earths  by  an 
alkali  hydroxide  or  oxalate.  To  remove  the  manganese 
and  calcium,  dissolve  the  precipitate  in  nitric  acid,  evapo- 
rate to  dryness,  and  heat  until  the  manganese  salt  is  decom- 
posed. Extract  with  water,  filter  off  the  oxide  of  man- 
ganese, treat  the  filtrate  with  ammonium  hydroxide,  and 


50  THE  R4RER  ELEMENTS. 

stir  thoroughly.  The  calcium  hydroxide  will  be  dissolved, 
and  the  yttrium  earths  precipitated. 

Experiment  2.  Precipitation  of  yttrium  hydroxide 
(Y(OH)3).  (a)  To  a  solution  of  an  yttrium  salt  add  am- 
monium hydroxide. 

(b)  Repeat  the  experiment,  using  sodium  or  potassium 
hydroxide. 

Note  the  insolubility  in  excess  in  each  case. 

(c)  Precipitate    yttrium   hydroxide    by    the    action    of 
ammonium  sulphide. 

Experiment  3.  Precipitation  of  yttrium  carbonate 
(Y2(CO3)3).  (a)  To  a  solution  of  an  yttrium  salt  add 
ammonium  carbonate. 

(b)  Repeat  the  experiment,  using  sodium  or  potassium 
carbonate.   • 

Note  the  solubility  in  the  cold  upon  the  addition  of  an 
excess  of  the  alkali  carbonates,  and  the  reprecipitation 
on  boiling. 

(c)  Try  the  action  of  the  common  acids  upon  yttrium 
carbonate. 

Experiment  4.  Precipitation  of  yttrium  oxalate 

(Y2(C2O4)3).  To  a  solution  of  an  yttrium  salt  add  a  solu- 
tion of  either  oxalic  acid  or  an  alkali  oxalate. 

Experiment  5.  Precipitation  of  yttrium  phosphates 
(Y2(HPO4)3;  YP04).  To  a  solution  of  an  yttrium  salt 
add  sodium  phosphate  in  solution  (Na2HPO4).  The  pre- 
cipitate is  said  to  be  of  the  acid  form  Y2(HP04)3.  The 
neutral  phosphate  (YPO4)  is  formed  by  treating  an  yttrium 
salt  in  solution  with  an  ammoniacal  phosphate. 

Experiment  6.  Precipitation  of  yttrium  ferrocyanide 
(YKFe(CN)6).  To  a  solution  of  an  yttrium  salt  add  potas- 
sium ferrocyanide. 

Experiment  7.  Precipitation  of  yttrium  chr  ornate 
(#Y2(CrO4)3-;yY2O3).  To  a  solution  of  an  yttrium  salt  add 
a  solution  of  potassium  chromate,  and  neutralize  if  necessary. 


THE   YTTRIUM  CROUP.  51 

Experiment  8.  Precipitation  of  yttrium  -fluoride  (YF3). 
To  a  solution  of  an  yttrium  salt  add  potassium  fluoride. 

Experiment  g.  Negative  tests  of  yttrium  salts.  Note 
that  hydrogen  sulphide  gives  no  precipitate  with  yttrium 
salts,  and  that  saturation  of  a  solution  of  an  yttrium  salt 
with  potassium  or  sodium  sulphate  gives  no  insoluble 
double  salt. 


2.  ERBIUM,  Er,  166  6.  YTTERBIUM,  Yb,  173 

3.  HOLMIUM,  Ho,  162  (NEOYTTERBIUM,  Ny,  170 ±) 

4.  THULIUM,  Tm,  171  (LUTECIUM,  Lu,  i74±) 

5.  DYSPROSIUM, Dy,  1 6 2. 5  7.  EUROPIUM,  Eu,  152 

8.  VICTORIUM,*  Vc,  117 

Discovery.  In  1843  Mosander  (J.  pr.  Chem.  xxx,  288) 
announced,  as  the  result  of  his  investigation  of  yttria,  its 
separation  into  three  earths,  two  white  and  one  yellow. 
To  the  less  basic  of  the  white  oxides  he  gave  the  name 
Terbium  earth,  to  the  more  basic  the  original  name  Yttrium 
earth,  and  the  yellow  oxide  he  called  Erbium  earth. 

In  1880  Cleve  (Compt.  rend.  LXXXIX,  478),  while  work- 
ing on  erbium  earth,  discovered  two  elements,  Holmium 
and  Thulium,  which  he  separated  as  the  oxides. 

Six  years  later  Lecoq  de  Boisbaudran  (Compt.  rend, 
en,  1004)  announced  the  isolation  of  a  new  earth  from  the 
oxide  of  holmium,  namely,  that  of  Dysprosium. 

In  1878  Marignac  (Compt.  rend.  LXXXVII,  578)  found  in 
gadolinite  the  oxide  of  a  new  element  which  he  named 
Ytterbium. 

In  1906  Auer  von  Welsbach  (Monatsheft?  f.  Chem. 
xxvii,  935)  announced  that  he  had  decomposed  ytterbium 
by  the  action  of  ammonium  oxalate  on  the  double  ammo- 

*  Considered  by  Urbain  (Jour.  chim.  phys.  iv,  321)  to  be  gadolinium. 


52  THE  RARER  ELEMENTS. 

nium  oxalate,  and  in  1907  Urbain  (Compt.  rend.  CXLV,  759; 
Chem.  News,  xcvi,  271)  stated  that  by  subjecting  Marignac's 
ytterbium  to  fractional  crystallization  in  nitric  acid  he  had 
separated  it  into  two  elements,  which  he  called  Neoytter- 
bium  and  Lutecium. 

Demarcay,  in  1901  (Compt.  rend,  cxxxn,  1484),  isolated 
a  colorless  earth  closely  associated  with  samarium,  and 
named  the  new  element  Europium.  This  earth,  the  exist- 
ence of  which  had  for  some  years  been  recognized  by  him- 
self and  by  others,  had  been  designated  by  him  as  2,  and  by 
Lecoq  de  Boisbaudran  as  Ze. 

In  1899  Crookes  (Chem.  News  LXXIX,  212)  separated 
from  the  yttrium  earths  by  fractional  fusion  of  the  nitrates 
and  fractional  crystallization  of  the  oxalates  a  new  substance 
having  a  group  of  lines  in  the  ultra  violet.  This  substance 
he  at  first  called  Monium  and  later  Victorium  (Proc.  Royal 
Soc.  LXV,  237). 

Occurrence.  These  very  rare  earths  are  found  in  small 
quantities  and  varying  proportions  associated  with  yttria 
(vid.  Occurrence  of  Rare  Earths,  page  35).  Their  chief 
sources  are  as  follows:  of  erbium,  gadolinite,  yttrotantalite, 
euxenite,  sipylite,  xenotime;  of  ytterbium,  gadolinite, 
sipylite,  xenotime,  euxenite ;  of  holmium,  thulium  and  dys- 
prosium, gadolinite,  keilhauite,  euxenite,  samarskite;  of 
europium,  samarskite,  orthite,  cerite,  gadolinite,  keilhauite; 
of  victorium,  crude  yttrium  earths. 

Extraction.  Methods  for  the  extraction  of  the  yttrium 
earths  have  been  already  given  (vid.  Extraction  of  Yttrium, 
page  46). 

Compounds.  A.  Typical  forms.  In  the  table  on  the  next 
page  are  given  typical  compounds  of  erbium  and  ytterbium. 

B.  Characteristics.  In  general  chemical  behavior  the 
compounds  of  the  yttrium  earths  resemble  closely  those  of 
yttrium.  The  salts  of  erbium  are  of  a  rosy  tint  and  give 
absorption  bands.  The  oxide  is  yellowish.  Ytterbium 


THE    YTTRIUM   GROUP. 


S3 


Er 

Yb 

Oxides    

Er,O, 

Yb,O, 

Hydroxides  

Er205 
Er2O(OH)4 

Yb2O,+6H2O 

Chlorides 

ErCl3 

YbCl,  +  3HaO 

Bromides 

ErBr3  +  9H3O 

Iodide             

ErI, 

Fluoride  

ErFj 

Chlorate  

Er(ClO3)j  +  8H2O 

Perchlorate  

Er(ClO4)j  +  8H2O 

Bromate  

Er(BrO,)3  +  9H2O 

lodate...  

Er(IO3)3  +  3H2O 

Sulphite 

Er,(SCOt  +  3H,O 

Sulphates 

Er,(S(X),  +  8H,O 

Yb,(SCO,  +  8H,O 

Double  sulphates  

Er,(SO/),-3K,S(X 

Dithionate  

Er2(S04)3.5Na2S04 
Er2(S04)3-(NH4)2S04 
Er2(SjOe),+  i8H,O 

Selenites  

Er-.fSeO.^+'jHjO 

Yb,(SeO,), 

Seleniate  

Er2(SeO4)3  +  5H2O 

Nitrate  

Er(NO3)3  +  6H2O 

Phosphate 

ErPO4  +  H,O 

Pvrophosphate 

Er,H,(PaO7),+  7H,O 

Carbonate                        . 

Er2O3  •  2CO2  +  2H2O 

Oxalates             .  .          .      . 

Er,(  C,CM,  +  1  2H,O 

Yb2fC,O4),  +  ioH,O 

Acetates  

Er(C,HsO2).  +  2HjO 

Yb(CjH,O,)a  +  2H,O 

Sulphide  

ErjS. 

forms  colorless  compounds  and  gives  no  absorption  bands. 
The  compounds  of  holmium,  thulium,  dysprosium,  europium, 
and  victorium  have  not  been  sufficiently  investigated  to 
warrant  description.  The  identification  of  members  of  this 
group  is  made  by  the  methods  of  spectrum  analysis. 

Separation.  For  the  separation  of  erbium  from  the 
other  members  of  the  yttrium  group  Methods  8,  9,  n,  12,  13, 
20,  26(a),  and  28  (page  43)  are  used.  James  obtains  erbium 
by  his  bromate  process  (vid.  Separation  of  Yttrium,  page  48) 
in  the  fraction  between  yttrium  and  thulium. 

In  separating  ytterbium,  Methods  8,  9,  n,  21,  26(0),  and 
28  are  recommended.  In  the  bromate  process  this  earth  is 
to  be  found  in  the  mother  liquor  after  the  separation  of  the 
fractions  containing  the  other  members  of  the  group. 

Holmium  has  been  separated  by  Methods  i,  n,  13,  2 6 (a), 


54  THE   RARER   ELEMENTS. 

and  28.  It  is  found  in  the  bromate  process  in  the  fraction 
between  dysprosium  and  yttrium. 

For  thulium  Methods  8,  25(6),  and  28  have  been  recom- 
mended. It  crystallizes  in  the  bromate  process  in  the  last 
fraction  following  the  erbium. 

Dysprosium  has  been  separated  by  Methods  n,  2 6 (a), 
and  28.  The  bromate  of  this  earth  crystallizes  between 
terbium  and  holmium. 

Methods  26  (c)  and  (d)  have  been  especially  effective  in 
separating  europium.  James  finds  the  main  portion  of  the 
europium  with  the  cerium  earths,  especially  samarium,  after 
the  treatment  with  sodium  sulphate.  When  lanthanum, 
praseodymium,  neodymium,  samarium,  europium,  and  gado- 
linium are  subjected  to  fractional  crystallization  as  the 
double  magnesium  nitrates,  europium  appears  in  the  last 
fraction  before  gadolinium  and  following  samarium. 

Methods  8,  21,  and  2 6 (a)  have  been  used  in  separating 
victorium.  Crookes  finds  that  its  oxalate  is  precipitated 
in  nitric  acid  solution  after  terbium  and  before  yttrium. 


II.  THE  TERBIUM  GROUP, 
i.  TERBIUM,  Tr,  159  2.  GADOLINIUM,  Gd,  156 

Discovery.  Terbium  was  first  isolated  by  Mosander  in 
1843  (vid.  Discovery  of  Erbium). 

In  1886  Marignac  and  Lecoq  de  Boisbaudran  (Compt. 
rend,  cii,  902)  separated  from  terbium  earth  the  oxide  of  an 
unknown  element  named  by  them  Gadolinium. 

Occurrence.  These  earths  are  found  in  small  quantities 
associated  with  the  yttrium  earths  (vid.  Occurrence  of  Rare 
Earths,  page  35).  The  chief  sources  of  terbium  are  gado- 
linite,  samarskite,  euxenite,  and  monazite;  of  gadolinium, 
samarskite  and  orthite. 


THE   TERBIUM  GROUP. 


55 


Extraction.  These  earths  are  extracted  from  minerals 
with  the  members  of  the  yttrium  group  (vid.  Extraction  of 
Yttrium,  page  46) . 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  terbium  and  gadolinium : 


Tr 

Gd 

Oxide 

Tr2O3 

Hydroxide     

Tr2O3  +  6H2O 

Chloride  

GdCl3  +  6H2O 

Bromide  

GdBr3  +  6H2O 

Sulphate             

Tr2(SO4),  +  8H2O 

Double  sulphate        

Gd2(SO4)3-  K2SO4+  2H2O 

Nitrates           

Tr(NO3)3  +  6H2O 

Gd(NO3)3  +  5H2O 

Double   nitrate 

2Gd(NO3)3  •  3Ni(NO3)  -  +  24H2O 

Carbonates 

Tr,fCO,),  +  #H,O 

Gd2(CO3)34-i3H2O 

Acetates 

Tr(C,H,O,), 

Gd(  C,H,O,),  +  4H,O 

B.  Characteristics.  The  compounds  of  the  terbium 
earths  are  very  similar  in  chemical  form  and  behavior  to 
those  of  the  yttrium  earths.  The  members  of  this  group  are 
distinguished  from  the  yttrium  earths,  with  the  exception 
of  europium  and  victorium,  on  the  one  hand,  and  from  the 
cerium  earths  on  the  other,  in  that  their  double  potassium 
sulphates  are  more  insoluble  in  a  saturated  solution  of 
potassium  sulphate  than  the  corresponding  salts  of  the 
former  group,  and  less  insoluble  than  those  of  the  latter. 

Separation.  Methods  8,  n,  18,  19,  26  (a),  and  28  (page 
43)  have  been  used  in  separating  terbium  from  other  rare 
earths.  James  separates  terbium  from  the  cerium  earths 
by  saturation  with  sodium  sulphate.  On  conversion  of  the 
yttrium  earths  together  with  terbium  into  the  bromates, 
and  crystallization,  the  terbium  separates  in  the  first  frac- 
tion. Gadolinium  has  been  separated  by  Methods  n,  23, 
2 6 (a),  (6),  (c),  (d),  and  29.  James  classifies  it  in  the  cerium 
group,  and  by  crystallization  of  the  double  magnesium 
nitrates  separates  it  in  the  last  fraction. 


56  THE  RARER  ELEMENTS. 

III.   THE   CERIUM   GROUP, 
i.  CERIUM,  Ce,  140.25. 

Discovery.  In  the  course  of  the  analysis  of  a  mineral 
from  Riddarhyttan,  Sweden,  in  1803,  Klaproth  discovered 
an  earth  which,  while  resembling  yttria  in  many  of  its 
reactions,  differed  from  it  in  being  insoluble  in  carbonate 
of  ammonium,  and  in  acquiring,  when  ignited,  a  light  brown 
color.  Because  of  this  latter  peculiarity,  the  name  Ochroite 
suggested  itself  to  him,  from  'ooXpot,  yellow  brown  (Phil. 
Mag.  xix,  95).  At  the  same  time,  and  independently  of 
Klaproth,  Berzelius  and  Hisinger  made  the  same  discovery. 
Their  name  for  the  new  element  was  Cerium,  chosen  in  honor 
of  the  discovery  of  the  planet  Ceres  by  Piazzi  in  1801  (Phil. 
Mag.  xx,  155;  xxn,  193). 

Occurrence.  Cerium  is  found  in  many  minerals,  asso- 
ciated, usually,  with  other  members  of  the  rare  earth 
group  (vid.  Occurrence  of  Rare  Earths,  page  35).  Its 
chief  sources  are  allanite,  monazite,  and  cerite. 

Extraction.  Cerium  is  generally  extracted  from  cerite 
through  decomposition  of  the  mineral  by  heating  it  with 
strong  sulphuric  acid  (vid.  Experiment  i).  The  decom- 
position may  be  accomplished  also  by  the  action  of  a  mix- 
ture of  strong  hydrochloric  and  nitric  acids,  but  better 
results  may  be  expected  by  the  former  method. 

The  Element.  A.  Preparation.  Elementary  cerium  may 
be  obtained  (i)  by  reducing  the  chloride  with  sodium  or 
potassium  (Mosander) ;  (2)  by  subjecting  the  double  chloride 
of  cerium  and  sodium  to  electrolysis  (Pogg.  Annal.  CLV,  633). 

B.  Properties.  In  appearance  cerium  resembles  iron. 
While  fairly  stable  in  dry  air,  it  oxidizes  quickly  in  moist  air. 
It  takes  fire  more  easily  than  magnesium,  and  melts  at  a 
lower  temperature  than  silver  and  at  a  higher  temperature 


CERIUM.  57 

than  antimony.  It  is  soluble  in  dilute  acids,  but  is  not 
attacked  by  concentrated  sulphuric  or  nitric  acid.  It  com- 
bines with  chlorine,  bromine,  and  iodine,  forming  salts.  Its 
specific  gravity  is  6.6. 

Compounds.     A.  Typical  forms.     The  following  are  typ- 
ical forms  of  the  two  classes  of  cerium  compounds: 

Oxides  ..........  Ce2O3  CeO2 

Hydroxides  .....  Ce2Os  •  6H2O  2CeO2  •  3H2O 

Carbonates  ......  Ce2(CO3)3+  sH,O  Ce(CO3)2-f  o.5H2O 

Chloride  ........  CeCl3 

Bromide  ........  CeBr, 

Iodide  ..........  CeI3 

Perchlorate  ......  Ce(ClO4)3+  8H2O 

Bromate  ........  Ce(BrO3)3+  QHjO 

lodate  ..........  Ce(IO3)3+  2H2O 

Fluorides  .......  CeF3  CeF4+H,O 

Cyanide  .........  Ce(CN)3 

Ferrocyanides.  .  .  Ce4(FeC0N6)3-f  3oH3O 

CeKFeC6N8+3H2O 
Ferricyanide  .....  CeFeC8Nc+  8H2O 

Sulphocyanide  .  .  Ce(CSN)3+  7H2O 
Sulphide  ........  Ce2S3 

Sulphite  ........  Ce2(SO3)3-f-  3H2O 

Sulphates  .......  Ce2(SO4)3+  3,  5,  6,  8,  9,  and     Ce(SO4)2+4H,O 

i2H2O 
Double  sulphates.  Ce2(SO4)3  •  3K2SO4+  2H2O         Ce(SO4)2  •  2K2SO4+  2H,O 

Ce2(S04)3-Na2S04+2H20 

Ce2(S04)3  •  (NH4)2S04+  8H2O 
Nitrates  ........  Ce(NO3)3+6H2O  Ce(NO3)4 

Double  nitrates.  .Ce2(NO3)9.3Zn(NO3)2+  2Ce(NO3)4-4KNO3+3H2O 


Ce2(N03)8.3Co(NO,)2+  2Ce(NO3)4.4(NH4)NO34- 

24H2O,  etc.  3H20 

Phosphates  ......  CePO4  (CeO2)4  •  (P2O5)6+  26H2O 

Oxalate  .........  Ce2(C2O4), 

Carbide  .........  CeC2 

B.  Characteristics.  Cerium  exists  in  compounds  in  two 
conditions  of  oxidation.  The  higher  or  eerie  salts  are 
easily  reduced  to  the  lower  or  cerous  condition  by  the 
ordinary  reducing  agents  (e.g.  H2S,  SO2,  H2C2O4,  etc.), 


$8  THE  RARER  ELEMENTS. 

and  the  cerous  salts  may  be  oxidized  to  the  eerie  condition 
by  oxidizing  agents  (e.g.  PbC^  +  HNOs,  ^2^2  in  alkaline 
solution,  KMnO4,  etc.).  In  general  the  cerous  salts  are 
colorless,  and  the  eerie  yellow.  The  lower  oxide  of  cerium, 
(Ce203),  on  ignition  goes  over  to  the  higher  condition, 
(Ce02).  The  cerous  salts  are  the  more  stable,  and  con- 
sequently they  form  the  greater  number.  They  resemble 
the  yttrium  salts  in  many  of  their  reactions,  and  are 
distinguishable  from  them  chiefly  by  the  greater  insolu- 
bility of  the  double  sulphates  with  sodium  sulphate  and 
potassium  sulphate  respectively  in  excess  of  the  alkali 
sulphate,  by  the  comparative  insolubility  of  the  carbonate 
in  ammonium  carbonate,  and  by  the  possibility  of  oxida- 
tion to  a  higher  condition.  Solutions  of  pure  cerium  salts 
give  no  absorption  bands. 

Estimation.  A.  Gravimetric.  Cerium  is  usually  deter- 
mined gravimetrically  as  the  dioxide,  (CeO2),  obtained  by 
the  ignition  of  the  hydroxide  or  the  oxalate. 

B.  Volumetric,  (i)  When  eerie  oxide,  (CeO2),  is  treated 
with  hydrochloric  acid  in  the  presence  of  potassium 
iodide,  iodine  is  set  free,  according  to  the  following 
equation  : 

2CeO2  +  8HC1  +  2KI  =  2CeCl3  +  4H2O  +  2KC1  +  12. 


The  iodine  may  be  estimated  in  acid  solution  by  stand- 
ard thiosulphate,  or  in  alkaline  solution  by  standard 
arsenious  acid  (Bunsen,  Ann.  Chem.  Pharm.  cv,  49  ;  Brown- 
ing, Amer.  Jour.  Sci.  [4]  vm,  451). 

(2)  When  cerium  oxalate  is  dissolved  in  sulphuric  acid 
the  'oxalic  acid  may  be  readily  determined  by  potassium 
permanganate  >   and  the  amount  of  cerium  present  may 
be  thus  estimated  (Stolba,  Zeitsch.  anal.  Chem.  xix,  194; 
Browning,  Amer.  Jour.  Sci.  [4]  vm,  457). 

(3)  When   yellow  eerie   compounds   are   treated   with 
hydrogen  dioxide  in  acid  solution,  they  are  reduced  to 


CERIUM.  59 

cerous  compounds,  with  bleaching  of  color  (Knorre,  Zeitsch. 
angew.  Chem.  (1897),  685): 


(4).  Cerium  may  be  estimated  in  the  presence  of  the 
other  rare  earths  by  precipitating  the  hydroxide  in  the  pres- 
ence of  potassium  ferricyanide,  filtering,  and  estimating  by 
potassium  permanganate  the  ferrocyanide  formed  (Drowning 
and  Palmer,  Amer.  Jour.  Sci.  xxvi  (1908),  83),  according 
to  the  equations: 

(1)  2K3FeC6N6  +  Ce2O3  +  2KOH  =  2K4FeC6N6  +  H2O  + 
2Ce02. 

(2)  5K4FeC6N6+KMn04+4H2SO4=  5 


Separation.  Cerium  falls  into  the  analytical  group 
with  aluminum,  iron,  etc.  Together  with  the  other  rare 
earths  it  may  be  separated  from  these  by  oxalic  acid  or 
oxalate  of  ammonium.  For  separation  from  the  yttrium 
earths,  vid.  page  48. 

Cerium  may  be  separated  from  lanthanum,  praseodym- 
ium, and  neodymium  by  the  following  methods:  (i)  by 
treating  the  hydroxides  suspended  in  a  solution  of  caustic 
potash  with  chlorine  gas,  as  in  Experiment  i  (Mosander,  J. 
pr.  Chem.  xxx,  267)  ;  (2)  by  treating  a  neutral  solution  of  the 
cerium  earths  with  an  excess  of  a  hypochlorite  and  boiling, 
thus  precipitating  eerie  oxide  (Popp,  Ann.  Chem.  Pharm. 
cxxxi,  359)  ;  (3)  by  treating  a  solution  of  the  cerium  earths 
with  sodium  peroxide,  in  place  of  the  hypochlorite  in  (2)  (0. 
N.  Witt,  Chem.  Ind.  (1896),  u,  19)  ;  (4)  by  treating  the  oxa- 
lates  of  the  cerium  earths  with  warm  dilute  nitric  acid,  thus 
separating  the  cerium  as  basic  nitrate  (Auer  von  Welsbach, 
Monatshefte  f.  Chem.  v,  508)  ;  (5)  by  treating  a  solution  of 


60  THE  R/tRER   ELEMENTS. 

the  salts  with  hydrogen  dioxide  in  the  presence  of  magnesium 
acetate  (Meyer  and  Koss,  Ber.  Dtsch.  chem.  Ges.  xxxv,  672)  ; 
(6)  by  treating  the  neutralized  nitrate  solution  with  an  ex- 
cess of  zinc  oxide  and  adding  potassium  permanganate,  thus 
precipitating  cerium  peroxide;  (7)  by  the  action  of  chromic 
acid  on  the  hydroxides,  dissolving  the  cerium  (Esposito, 
Proc.  Chem.  Soc.  xxn,  20). 

From  thorium  cerium  may  be  separated  (i)  by  repeated 
precipitations  on  boiling  with  sodium  thiosulphate  (Fre- 
senius  and  Hintz,  Zeitsch.  anal.  Chem.  xxxv,  543)  ;  (2)  by 
boiling  with  potassium  trinitride  (Dennis  and  Kortright, 
Amer.  Chem.  Jour,  xvi,  79)  : 


(3)  by  boiling  a  nearly  neutral  solution  of  the  chlorides 
with  copper  and  cuprous  oxide  (Lecoq  de  Boisbaudran, 
Compt.  rend,  xcix,'  525)  ;  (4)  by  the  action  of  fumaric 
acid  in  40%  alcohol  upon  solutions  of  the  sa1ts  in  40% 
alcohol  (Metzger,  Jour.  Amer.  Chem.  Soc.  xxiv,  901)  ;  (5)  by 
oxidizing  cerous  salts  to  the  eerie  condition  and  treating 
with  ammonium  oxalate,  cerium  not  being  precipitated  at 
first  (Orlow,  Chem.  Ztg.  xxx,  733).  In  all  of  these  methods 
the  thorium  is  precipitated. 

Cerium  is  separated  from  zirconium  by  fusion  of  the 
oxides  with  acid  potassium  fluoride,  and  extraction  with 
water  and  a  little  hydrofluoric  acid;  the  potassium  fluo- 
zirconate  is  dissolved,  and  the  thorium  and  cerium  remain* 
(Delafontaine,  Chem.  News  LXXV,  230). 

In  addition  to  the  foregoing,  Methods  i,  3,  4,  6-10,  18, 


*  For  the  action  of  organic  bases  as  precipitants  of  the  rare  earths,  vid. 
Jefferson,  Jour.  Amer.  Chem.  Soc.  xxiv,  540;  Baskerville,  Science,  New 
Series,  xvi,  215;  Kolb,  J.  pr.  Chem.  [2]  LXVI,  59;  Allen,.  Jour.  Amer.  Chem. 
Soc.  xxv,  421  ;  Holmberg,  Chem.  Zentral.  1906,  II,  1595. 


THE  CERIUM   GROUP.  61 

and  26(6),  page  43,  have  been  used  in  separating  cerium- 
from  its  associates. 

Experimental  Work.     Vid.  end  of  the  chapter. 

2.  LANTHANUM,  La,  138.9  5.  SAMARIUM,  Sm,  150.3 

2.  NEODYMIUM,  Nd,  143.6  6.  SCANDIUM,  Sc,  44.1 

4.  PRASEODYMIUM,  Pr,  140.5        6.  DECIPIUM,  Dp,  171 

Discovery.  In  1839  Mosander  found  that  when  the 
nitrate  of  cerium  had  been  ignited,  he  was  able  to  extract 
from  it  by  very  dilute  acid  an  earth  which  differed  in  prop- 
erties from  that  of  cerium,,  while  from  the  portion  remain- 
ing undissolved  he  obtained  the  reactions  of  the  cerium 
earth.  He  supposed  the  unknown  substance  of  the  newly 
discovered  earth  to  be  an  element,  and  named  it  Lan- 
thanum, from  \avQaveiv,  to  hide  (Pogg.  Annal.  XLVI,  648; 
Liebig,  Annal.  xxxn,  235). 

In  1841,  while  engaged  in  further  work  upon  the  extrac- 
tion of  mixtures  of  cerium  and  lanthanum  oxides  by  dilute 
nitric  acid,  he  succeeded  in  separating  from  the  lanthanum 
oxide  another  earth,  rosy  in  color,  going  over  to  dark  brown 
on  being  heated.  Reserving  for  the  residual  oxide  the 
original  name  Lanthanum  earth,  he  called  the  base  of  the 
new  oxide  Didymium,  from  didvj^os,  twin, — a  name  sug- 
gested by  its  close  relationship  to  lanthanum  and  its 
almost  invariable  occurrence  with  it  (Pogg.  Annal.  LVI,  503). 

In  1885  Auer  von  Welsbach  announced  that  by  long- 
continued  fractional  crystallization  of  the  double  nitrates 
of  ammonium  with  lanthanum  and  didymium  in  the  pres- 
ence of  strong  nitric  acid,  he  had  separated  didymium 
into  two  elements  (Sitzungsber.  d.  k.  Acad.  d.  Wiss.  (1885) 
xcn,  Heft  I,  n,  317;  Ber.  Dtsch.  chem.  Ges.  xvm,  605). 
The  lanthanum  crystallized  out  first,  and  afterward  the 
decomposition  of  the  didymium  took  place.  To  these 
new  elements  he  gave  the  names  Praseodymium  (T 
leek-green)  and  Neodymium  (Veos-,  new). 


62  THE  RARER  ELEMENTS. 

In  1888  Kriiss  and  Nilson  stated,  as  the  result  of  their 
work  on  the  absorption  spectrum  of  didymium,  that  they 
had  discovered  indications  of  the  presence  of  no  less  than 
eight  elements  (Ber.  Dtsch.  chem.  Ges.  xx,  2134,  3067). 
These  results,  however,  have  not  as  yet  been  confirmed. 
At  the  present  time  the  existence  of  praseodymium  and 
neodymium  is  accepted. 

In  1878  Delafontaine  (Compt.  rend.  LXXXVII,  559,  632) 
announced  the  discovery  of  Decipium  m  a  North  Carolina 
samarskite. 

In  1879  Nilson  (Ber.  Dtsch.  chem.  Ges.  xn,  554),  while 
engaged  in  extracting  ytterbium  from  euxenite,  separated 
an  earth  of  much  lower  atomic  weight,  the  unknown  element 
of  which  he  called  Scandium.  The  same  year  Lecoq  de 
Boisbaudran  (Compt.  rend.  LXXXVIII,  323),  in  the  course  of 
an  examination  of  the  absorption  spectra  of  the  earths 
separated  from  samarskite,  isolated  the  earth  of  another 
new  element,  Samarium. 

Occurrence.  The  cerium  earths  occur  closely  associated 
with  cerium.  The  following  are  some  of  the  chief  sources: 
of  lanthanum,  cerite,  allanite,  monazite,  bastnaesite,  and 
lanthanite ;  of  praseodymium  and  neodymium,  cerite,  altan- 
ite,  monazite,  and  bastnaesite;  of  samarium,  samarskite, 
orthite,  cerite,  gadolinite,  and  keilhauite;  of  scandium, 
gadblinite,  yttrotitanite,  euxenite,  and  keilhauite;  of  decip- 
ium,  samarskite. 

Extraction.  In  the  process  of  extracting  cerium  from 
cerite  (vid.  Experiment  i)  the  oxalates  of  the  cerium  earths 
are  precipitated  together. 

The  Elements.  I.  LANTHANUM.  A.  Preparation.  The 
element  lanthanum  may  be  obtained  (i)  by  reducing  the 
chloride  with  potassium;  (2)  by  subjecting  the  double 
chloride  of  lanthanum  and  sodium  to  electrolysis. 

B.  Properties.  Lanthanum  is  a  metallic  element  of  a 
lead-gray  color.  It  decomposes  cold  water  slowly  and  hot 


THE   CERIUM   GROUP.  63 

water  more  rapidly,  with  the  evolution  of  hydrogen.  It 
oxidizes  easily  in  the  air.  Its  specific  gravity  is  from  6.04 
to  6.19. 

II.  PRASEODYMIUM    AND    NEODYMIUM.    The    elements 
praseodymium  and  neodymium  have  not  been  isolated.     A 
mixture  of  the  two,  known  as  didymium,  has  been  prepared 
by  the  methods  used  for  lanthanum.     Didymium  is  yellow- 
ish \vhit3  in  color.      It  decomposes  cold  water  slowly  and 
oxidizes  in  air.     Its  specific  gravity  is  6.54. 

III.  SAMARIUM,  SCANDIUM,  AND  DECIPIUM.     These  ele- 
ments have  not  been  isolated. 

Compounds.  A .  Typical  forms.  In  the  table  on  the  next 
page  are  shown  typical  compounds  of  the  members  of  the 
cerium  group  other  than  cerium. 

B.  Characteristics.  The  compounds  of  the  other  mem- 
bers of  the  cerium  group  are  very  similar  to  those  of  cerium 
in  the  cerous  condition  in  their  behavior  toward  chemical 
reagents.  They  may  be  distinguished  from  the  compounds 
of  cerium  by  the  absence  of  yellow  color  on  the  addition  of 
oxidizing  agents, — a  color  characteristic  of  the  higher  oxide 
of  cerium.  Lanthanum  may  be  distinguished  from  praseo- 
dymium and  neodymium  by  the  colorlessness  of  its  salts  and 
by  the  absence  of  an  absorption  spectrum.  Didymium  salts 
in  general  are  of  a  rosy  color  and  give  a  distinctive  absorption 
spectrum. 

Neodymium  salts  are  rose-colored  and  are  very  similar 
in  appearance  and  behavior  to  the  salts  of  didymium.  The 
oxide  Nd2Os  is  bluish.  Praseodymium  salts  are  green. 
While  their  chemical  form  resembles  closely  that  of  the  neo- 
dymium salts,  higher  oxides  are  definitely  known  in  the 
case  of  praseodymium.  The  ordinary  oxide  Pr2O3  is  green- 
ish white ;  the  higher  oxide  Pr4O7  is  nearly  black.  Each  of 
the  two  elements  has  distinctive  spectra,  spark  and  absorp- 
tion. Mixed,  the  elements  give  the  didymium  spectrum. 
The  lower  oxide  and  the  salts  of  samarium  are  yellow 


THE  RARER  ELEMENTS. 


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THE  CERIUM  GROUP,  65 

Solutions  of  the  salts  give  characteristic  absorption  bands. 
The  oxides  and  salts  of  scandium  and  decipium  are  colorless. 
The  salts  show  no  absorption  spectrum. 

Estimation.  Like  cerium,  the  other  members  of  its 
group  are  generally  estimated  as  oxides,  obtained  by  ignition 
of  the  hydroxides  or  oxalates. 

Separation.  A.  Lanthanum  from  didymium.  Lantha- 
num may  be  separated  from  didymium  (i)  by  dissolving 
the  sulphates  in  water  at  9°  C.  and  gradually  raising  the 
temperature, — the  lanthanum  sulphate  separating  first 
(Hermann,  J.  pr.  Chem.  LXXXII,  385);  (2)  by  heating  the 
nitrates  at  4oo°-5oo°  C.  and  extracting  with  water, — the 
didymium  tending  to  form  an  insoluble  basic  nitrate 
(Damour  and  Deville,  Bull.  Soc.  Chim.  d.  Paris,  n,  339) ; 
(3)  by  dissolving  half  of  a  given  amount  of  the  oxides  in 
warm  dilute  nitric  acid,  then  adding  the  other  half,  with 
constant  stirring,  cooling  the  mass,  and  extracting  with 
water  (vid.  Experiment  i), — the  didymium  being  found  in 
the  residue  (Auer  von  Welsbach,  Monatshefte  f.  Chem.  v, 
508) ;  (4)  by  fractional  crystallization  of  the  double  mag- 
nesium nitrates, — the  lanthanum  appearing  in  the  first 
crystallizations  (James,  Jour.  Amer.  Chem.  Soc.  xxx,  979). 

Separation  Methods  i,  9,  n,  12,  17-23,  25(6),  and  26(0), 
(6),  and  (c),  page  43,  have  also  been  used  in  separating  lan- 
thanum. 

B.  Praseodymium  from  neodymium.  Didymium  may 
be  separated  into  its  two  constituents  (i)  by  making  several 
hundred  fractional  crystallizations,  first  of  the  double 
nitrate  of  ammonium  and  didymium  and  later  of  the  double 
nitrate  of  sodium  and  didymium,  in  the  presence  of  lanthanum 
and  nitric  acid. — the  neodymium  salt  being  the  more  soluble 
(Auer  von  Welsbach,  Sitzungsber.  d.  k.  Acad.  d.  Wiss. 
(1885)  xcn,  Heft  I,  n,  317);  (2)  by  allowing  nitric  acid  to 
act  upon  the  oxalates, — the  praseodymium  salt  being  the 
more  soluble  (Scheele,  Ber.  Dtsch.  chem.  Ges.  xxxn,  417); 


66  THE  RARER  ELEMENTS. 

(3)  by  treating  the  sulphates  with  water, — the  praseo- 
dymium sulphate  being  the  more  soluble  (Muthmann  and 
Rolig,  Ber.  Dtsch.  chem.  Ges.  xxxi,  1718);  (4)  by  making 
fractional  precipitations  of  a  solution  of  didymium  nitrate 
by  means  of  sodium  acetate  and  hydrogen  peroxide, — the 
praseodymium  separating  first  (Meyer  and  Koss,  Ber.  Dtsch. 
chem.  Ges.  xxxv,  676) ;  (5)  by  making  fractional  crystalliza- 
tions of  the  double  magnesium  nitrates, — the  praseodymium 
appearing  first  after  the  lanthanum  (vid.  (4),  Separation  of 
Lanthanum  from  Didymium).  Methods  i,  8 (a),  9,  n,  12, 
19,  22,  23,  and  2 6 (a),  page  43,  have  also  been  used  in  the 
separation  of  praseodymium  and  neodymium  from  their 
associates  and  from  each  other. 

Samarium,  together  with  gadolinium  and  europium,  is 
found  by  James  in  the  mother  liquors  obtained  during  the 
fractionationof  the  double  magnesium  nitrates  of  lanthanum, 
praseodymium,  and  neodymium.  Urbain  and  Lacomb 
(Compt.  rend,  cxxxvn,  792,  and  cxxxvin,  84)  have  found 
that  the  addition  of  bismuth-magnesium  nitrate  helps  in  the 
separation.  The  samarium  appears  in  the  least  soluble 
fractions.  Vid.  also  Methods  9,  n,  20,  23,  and  2 6 (a),  (6), 
and  (d),  page  43. 

Scandium  is  obtained  with  ytterbium  by  James  in  the 
mother  liquors  from  the  bromate  crystallizations  (vid.  dia- 
gram, page  45).  It  is  separated  from  ytterbium  by  pre- 
cipitation as  the  double  potassium  sulphate.  Vid.  also 
Methods  8  and  21,  page  43. 

Decipium  may  be  separated  from  the  terbium  earths  by 
fractional  precipitation  with  potassium  sulphate.  The 
double  sulphate  of  decipium  and  potassium  is  among  the 
most  soluble  double  potassium  sulphates  of  the  cerium 
group,  but  is  less  soluble  than  the  corresponding  salts  of  the 
yttrium  and  terbium  groups.  Vid.  also  Methods  8,  n,  20, 
and  22,  page  43. 


EXPERIMENTAL    WORK  ON   THE  CERIUM  GROUP.  67 

EXPERIMENTAL    WORK    ON    CERIUM,    LANTHA- 
NUM,  PRAESEODYMIUM,   AND  NEODYMIUM. 

Experiment  i.  Extraction  of  cerium,  lanthanum,  and 
didymium  salts  from  cerite  (Ca,Fe)(CeO)(Ce2-3OH)(SiO3)3. 
Treat  25  grm.  of  finely  powdered  cerite  with  common 
sulphuric  acid  and  stir  until  the  mass  has  the  con- 
sistency of  thick  paste.  Heat  until  the  excess  of  sul- 
phuric acid  is  removed  and  then  keep  the  mass  for 
some  time  at  low  redness.  Cool,  pulverize,  and  digest 
with  cold  water  until  no  further  precipitate  appears  upon 
the  addition  of  ammonium  oxalate  to  a  few  drops  of  the 
extract.  Pass  hydrogen  sulphide  into  the  solution  to 
remove  traces  of  bismuth  and  copper.  Filter,  and  to  the 
filtrate  add  oxalic  acid  to  complete  precipitation  of  the 
oxalates  of  cerium,  lanthanum,  and  didymium.  Ignite  the 
oxalates,  and  dissolve  in  hydrochloric  acid  the  oxides 
obtained.  To  this  solution  add  potassium  hydroxide 
until  the  precipitation  of  the  hydroxides  is  complete. 
Make  up  the  volume  of  the  liquid  in  which  the  hydroxides 
are  suspended  to  about  200  cm.3  Add  about  5  grm.  of 
potassium  hydroxide  to  insure  an  excess,  and  pass  a  slow 
current  of  chlorine  gas  through,  stirring  from  time  to  time,, 
until  the  liquid  is  no  longer  alkaline  in  reaction  and  the 
precipitate  has  assumed  a  deep-yellow  color.  By  this 
process  the  cerium  hydroxide  is  oxidized  to  the  dioxide, 
which  remains  undissolved,  and  the  lanthanum  and  didy- 
mium hydroxides  are  dissolved.  When  the  separation  is 
complete,  a  portion  of  the  washed  precipitate  dissolved  in 
hydrochloric  acid  should  give  no  evidence  of  the  presence 
of  didymium, — for  example,  no  absorption  spectrum  (vid. 
Experiment  12).  The  absence  of  didymium  at  this  point 
is  considered  sufficient  evidence  of  the  absence  of  lanthanum. 
To  the  solution  containing  the  lanthanum  and  didymium, 


68  THE  R/tRER  ELEMENTS 

the  cerium  dioxide  having  been  removed  by  filtration,  add 
oxalic  acid  until  the  precipitation  is  complete.  Filter 
off  the  oxalates,  wash,  dry,  and  ignite.  Dissolve  one  half 
of  the  oxides  obtained  by  this  process  in  the  least  possible 
amount  of  warm,  dilute  nitric  acid,  and  add  the  remainder 
of  the  oxides  to  the  solution.  Stir  thoroughly,  and  when 
the  mass  is  cool  extract  with  water.  The  didymium  tends 
to  be  in  the  residue  and  the  lanthanum  in  solution. 

Experiment  2.  Reduction  and  oxidation  of  cerium 
compounds,  (a)  To  a  small  portion  of  the  carefully  washed 
cerium  dioxide  .obtained  in  the  previous  experiment  add 
a  little  hydrochloric  acid  diluted  with  an  equal  volume 
of  water  and  boil.  Note  the  evolution  of  chlorine  and 
the  ultimate  colorless  solution  of  cerium  chloride,  (CeCl3). 

(b)  To  a  portion  of  the  solution  obtained  in  (a)   add 
a  few  drops  of  ammonium  hydroxide  in  excess  and  some 
hydrogen  dioxide.     Note  the  orange  to  red-brown  precipi- 
tate (Ce03?).    Other  oxidizing  agents,  such  as  sodium  hypo- 
chlorite,   sodium   peroxide,   lead   dioxide,   potassium  per- 
manganate, etc.,  may  be  used.     Boil  the  solution  holding 
the  precipitate  in  suspension  and  note  that  the  deep-yellow 
color  changes  to  a  lighter  yellow.     The  precipitate  becomes 
essentially  the  dioxide,  (CeO2). 

(c)  To  another  portion  of  the  washed  cerium  dioxide 
from  Experiment    i   (2CeO2-3H2O)  add  hydrochloric  acid 
as  before,  and  also  a  crystal  of  potassium  iodide  in  the 
cold.      Note    the   liberation    of   iodine   according    to    the 
reaction  2Ce02  +  8HC1  +  2KI  =  2CeCl3  +  2KC1  + 12  +  4H2O. 

Experiment  3.  Formation  of  eerie  nitrate,  (Ce(NO3)4). 
Dissolve  in  nitric  acid  a  portion  of  the  hydrated  eerie  oxide 
formed  in  Experiment  i.  Note  the  orange-red  color. 

Try  the  action  of  hydrogen  dioxide  and  oxalic  acid 
upon  separate  portions  of  the  solution, 

Experiment  4.  Precipitation  of  cerous  hydroxide, 
(Ce(OH)3).  (a)  To  a  solution  of  cerium  chloride  add 


EXPERIMENTAL   WORK  ON   THE  CERIUM  GROUP.  69 

sodium,  potassium,  or  ammonium  hydroxide  in  solution. 
Note  the  insolubility  of  the  hydroxide  in  excess  of  these 
reagents. 

(b)  Repeat  the  experiment  with  tartaric  acid  present 
in  the  solution. 

Experiment  5.  Precipitation  of  cerous  carbonate, 
(Ce2(CO3)3).  (a)  To  a  solution  of  cerium  chloride  add  a 
solution  of  sodium  or  potassium  carbonate.  Note  the 
comparative  insolubility  in  excess. 

(b)  Repeat  the  experiment,  using  ammonium  carbonate 
as  the  precipitant. 

(c)  Try  the  action  of  the  common  acids  upon  the  car- 
bonate of  cerium. 

Experiment  6.  Precipitation  of  cerium  oxalate, 
(Ce2(C2O4)3).  (a)  To  a  solution  of  a  cerium  salt  add  oxalic 
acid  or  an  oxalate.  Note  the  crystalline  character  of  the  pre- 
cipitate, especially  after  the  liquid  has  been  stirred  and  boiled. 

(b)  Try  the  action  of  hydrochloric  acid  upon  cerium 
oxalate. 

Experiment  7.  Precipitation  of  the  double  sulphate 
of  cerium  and  potassium  or  sodium,  (Ce2(SO4)3-3K2SO4  or 
Ce2(S04)3-Na2S04).  To  a  few  drops  of  a  concentrated 
solution  of  a  cerous  salt  add  a  small  portion  of  a  saturated 
solution  of  sodium  or  potassium  sulphate. 

Experiment  8 .  Precipitation  of  cerium  phosphate,  (CePO4) . 
(a)  To  a  solution  of  a  cerous  salt  add  sodium  phosphate  in 
solution. 

(b)  Try  the  action  of  hydrochloric  and  acetic  acids  upon 
separate  portions  of  the  precipitate. 

Experiment  9.  Precipitation  of  cerous  fluoride,  (CeFa). 
To  a  solution  of  cerium  chloride  add  potassium  fluoride  in 
solution. 

Experiment  10.  Precipitation  of  the  ferrocyanide  of 
cerium,  (Ce^FeCeNe)  3) .  (a)  To  a  solution  of  cerium  chloride 
add  potassium  ferrocyanide. 


7o  THE  RARER  ELEMENTS.  . 

(b)  Note  that  potassium  ferricyanide  gives  no  precipi- 
tate. 

Experiment  n.  Comparison  of  lanthanum  and  didym- 
ium  with  cerium,  (a)  Perform  Experiments  4  to  10  in- 
clusive upon  dilute  solutions  of  lanthanum  and  didymium 
salts. 

(b)  Note  that  pure  lanthanum  and  didymium  salts  give 
no  change  of  color  with  oxidizing  agents.  Compare  with 
cerium  salts  (vid.  Experiment  2). 

Experiment  12.  Didymium  absorption  spectrum.  Place 
a  solution  of  a  didymium  salt  between  the  slit  of  the 
spectroscope  and  a  luminous  flame.  Note  the  dark  bands. 
Observe  that  cerium  and  lanthanum  salts  in  solution  show 
no  absorption  bands  when  free  from  didymium. 

Experiment  13.  Separation  of  praseodymium  and  neo- 
dymium.  If  time  and  material  allow,  an  interesting  experi- 
ment may  be  performed  by  taking  about  100  grm.  of  the 
oxides  of  lanthanum  and  didymium  (praseodymium  and 
neodymium),  dissolving  them  in  a  known  amount  of  nitric 
acid,  neutralizing  an  equal  amount  of  nitric  acid  by  means  of 
magnesium  oxide,  mixing  the  two  solutions,  and  proceeding 
with  the  fractional  crystallization  of  the  double  nitrates  to 
the  point  where  change  of  color  indicates  the  separation  of 
praseodymium  and  neodymium.  Observe  the  differences 
in  the  absorption  bands. 

Experiment  14.  Negative  test  of  the  salts  of  cerium, 
lanthanum  and  didymium.  Note  that  hydrogen  sulphide 
gives  no  precipitate  with  salts  of  this  group.  Ammonium 
sulphide  precipitates  the  hydroxides,  not  the  sulphides. 

IV.  THORIUM .*    Th.  232.5. 

Discovery.  As  early  as  the  year  1818  Berzelius,  working 
on  a  mineral  from  Fahlun,  Sweden,  believed  that  he  had 
discovered  a  new  earth  (Annal.  der  Phys.  u.  Chem.  (1818) 

*  For  a  discussion  of  radio  active  properties,  see  Chapter  III. 


THORIUM.  7  r 

xxix,  247).  He  gave  it  the  name  Thoria,  from  Thor,  son 
of  the  Scandinavian  war  god  Odin.  Some  years  later,  how- 
ever, he  identified  the  supposed  new  earth  as  chiefly  a  basic 
phosphate  of  yttrium  (Pogg.  Annal.  iv,  145).  In  1828  Es- 
mark  discovered,  near  Brevig,  Norway,  the  mineral  since 
known  as  thorite.  From  it  Berzelius  isolated  an  unknown 
earth ;  its  similarity  to  the  substance  described  by  him  some 
ten  years  earlier  prompted  the  name  Thoria  (Pogg.  Annal. 
xvi,  385). 

Occurrence.  Thorium  is  found  in  combination  in  cer- 
tain rare  minerals  (vid.  Occurrence  of  Rare  Earths,  page  35). 
Its  chief  sources  are  monazite,  thorianite,  and  thorite. 

Extraction.  Two  common  methods  for  the  extraction 
of  thorium  salts  are  here  indicated: 

(1)  From  thorite.     The  mineral  is  decomposed  by  heat- 
ing it  with  sulphuric    acid    (vid.  Cerium,  Experiment   i, 
page  67).    After  the  extraction  of  the  sulphate  with  cold 
water,   the  solution   is  heated  to  100°  C.  and  an  impure 
sulphate  of  thorium  comes  down.     By  repeated  solution  of 
the  precipitate  in  cold  water  and  reprecipitation  by  means 
of  heat  a  pure  sulphate  is  finally  obtained  (Delafontaine, 
Ann.  Chem.  Pharm.  cxxxi,  100). 

(2)  From  monazite.      The    mineral   is   decomposed  by 
sulphuric  acid  and  the  oxalates  are  precipitated  by  oxalic 
acid  (vid.  Experiment  i). 

The  Element.  A.  Preparation.  Elementary  thorium 
may  be  obtained  (i)  by  heating  the  double  chloride  of 
thorium  and  potassium  with  metallic  sodium  (Nilson) ; 
(2)  by  reducing  the  double  fluoride  of  potassium  and 
thorium  with  potassium. 

B.  Properties.  Thorium  is  known  in  two  forms,  (i) 
that  of  a  grayish,  glistening  powder,  and  (2)  crystalline. 
It  is  stable  in  the  air,  and  does  not  decompose  water,  even 
at  100°  C.  When  heated  in  a  current  of  chlorine,  bromine, 
or  iodine  it  glows  and  forms  the  salt.  It  is  soluble  in 


72  THE  RARER  ELEMENTS. 

dilute  hydrochloric  and  sulphuric  acids,  in  concentrated 
sulphuric  acid  with  the  liberation  of  sulphur  dioxide,  and 
in  aqua  regia.  It  is  acted  upon  very  slowly  by  nitric 
acid,  and  is  not  attacked  by  the  alkali  hydroxides.  The 
specific  gravity  of  thorium  in  the  amorphous  condition 
is  10.97;  in  crystalline  form  11.2. 

Compounds.     A.  Typical  forms.     The  following  are  typ- 
ical compounds  of  thorium: 

Oxides,  ThO2;  Th2O7. 

Hydroxide,  Th(OH)4. 

Chlorides,  ThCl4;  also  double  salts  with  KC1  and  NH,C1. 

Oxychloride,  ThOCl. 

Bromide,  ThBr4. 

Iodide,  ThI4. 

Fluoride,  ThF4  +  4H2O. 

Chlorate,  Th(ClO3)4. 

Perchlorate,  Th(ClO4)4. 

Bromate,  Th(BrO3)4. 

lodate,  Th(IOJv 

Sulphide,  ThS2. 

Oxysulphide,  ThOS. 

Sulphite,  Th(SO3)2  +  H20. 

Sulphates,  Th(SO4)2  +  9H2O;  also  double  salts  with  K2S04; 

Na2SO4;  and  (NH4)2S04. 
Selenite,  Th(SeO3)2  +  H2O. 
Seleniate,  Th(SeO4)2  4-  9H2O. 
Nitrate,  Th(NO3)4+i2H2O. 
Borides,  ThB4,  ThB6. 
Phosphate,  Th3(PO4)4  +  4H2O. 
Pyrophosphate,  ThP2O7  +  2H2O. 
Ferrocyanide,  ThFe(CN)6+4H2O. 
Suicide,*  ThSi. 

*  Honigschmid,  Compt.  rend.  CXLII,  157,  CXLIII,  224. 


THORIUM.  73 


Silicate,  ThSiO4. 
Carbonates,  Th(CO3)2; 
Oxalate, 


B.  Characteristics.  The  compounds  of  thorium  resem- 
ble in  chemical  form  those  of  cerium  in  the  eerie  con- 
dition. Thorium  resembles  cerium  also  in  having  a  hy- 
droxide insoluble  in  the  alkali  hydroxides,  and  in  forming 
a  double  sulphate  with  potassium  sulphate,  insoluble  in 
excess  of  that  precipitant.  The  salts  of  thorium  are  colorless 
except  where  the  element  is  combined  with  an  acid  having  a 
color  of  its  own.  Possibly  the  most  distinctive  reactions  of 
thorium  compounds  are  the  ready  formation  of  a  soluble 
double  oxalate  when  ammonium  oxalate  is  added  in  excess 
to  a  thorium  salt  in  solution,  and  the  precipitation  of  the 
hydroxide  when  a  solution  of  a  thorium  salt  is  boiled  with 
potassium  hydronitride  (Dennis  and  Kortright,  Amer. 
Chem.  Jour,  xvi,  79). 

Estimation.  Thorium  is  ordinarily  estimated  as  the 
oxide  (ThO2),  obtained  by  ignition  of  the  hydroxide,  the 
nitrate,  or  the  oxalate. 

Separation.  Thorium,  together  with  the  rare  earths 
cerium,  yttrium,  zirconium,  etc.,  may  be  separated  from 
the  other  elements  by  oxalic  acid.  Methods  for  its  separa- 
tion from  yttrium  and  cerium  have  already  been  given  (vid. 
pages  48  and  60). 

From  zirconium  thorium  may  be  separated  (i)  by  the 
action  of  acids  upon  the  potassium  double  sulphates,  — 
the  zirconium  salt  being  the  more  soluble;  (2)  by  the  action 
of  an  excess  of  hydrochloric  acid  upon  the  soluble  double 
ammonium  oxalates,  —  the  zirconium  remaining  in  solution; 
(3)  by  fusion  with  acid  potassium  fluoride;  (4)  by  the  action 
of  dimethylamine  upon  solutions  of  the  salts,  —  thorium 
hydroxide  being  precipitated  (Kolb,  J.  pr.  Chem.  [2]  LXVI, 
59). 


74  THE  RARER  ELEMENTS. 


EXPERIMENTAL  WORK  ON  THORIUM. 

Experiment  i .  Extraction  of  thorium  oxide  from  mono,- 
zite.  Treat  25  grm.  of  finely  ground  monazite  with  com- 
mon sulphuric  acid,  according  to  the  method  already 
described  (vid.  Experiment  i,  page  67).  Precipitate  the 
oxalates  with  oxalic  acid, — not  ammonium  oxalate, — boil, 
and  collect  on  a  filter.  Treat  the  precipitate  with  a  large 
excess  of  ammonium  oxalate  and  boil.  Cool,  dilute,  filter, 
and  to  the  filtrate  add  hydrochloric  acid.  Collect  and  ignite 
the  oxalate  of  thorium  thus  precipitated. 

Note.  This  method  may  be  employed  for  the  extraction 
of  thorium  from  discarded  Welsbach-light  mantles. 

Experiment  2.  Precipitation  of  thorium  hydroxide, 
(Th(OH)4).  (a)  To  a  solution  of  a  thorium  salt  add  sodium, 
potassium,  or  ammonium  hydroxide.  Note  the  insolubility 
of  the  hydroxide  in  excess  of  the  precipitant. 

(b)  To  a  solution  of  a  thorium  salt  add  sodium  thio- 
sulphate  in  solution  and  boil. 

Experiment  3.  Precipitation  of  thorium  'carbonate, 
(Th(C03)2).  (a)  To  a  solution  of  a  thorium  salt  add 
potassium  or  sodium  carbonate.  Note  the  solubility  of 
the  precipitate  in  excess  and  the  reprecipitation  on  boiling. 

(b)  Repeat,  using  ammonium  carbonate. 

(c)  Note  the  solvent  action  of  the  common  acids  upon 
thorium  carbonate. 

Experiment  4.  Precipitation  of  the  oxalate  of  thorium, 
(Th(C2O4)2  +  2H2O).  (a)  To  a  solution  of  a  thorium  salt 
add  a  solution  of  oxalic  acid.  Note  the  insolubility  in 
excess  of  the  precipitant. 

(b)  Repeat,  using  ammonium  oxalate  as  the  precipitant. 

Note  the  solubility  in  excess,  especially  on  warming,  and 

'  the  reprecipitation  upon  the  addition  of  hydrochloric  acid. 


ZIRCONIUM.  75 

(c)  Try  the  solvent  action  of  ammonium  acetate  upon 
thorium  oxalate. 

Experiment  5.  Precipitation  of  the  double  sulphate 
of  potassium  and  thorium,  (Th(SO4)2-2K2SO4  +  2H2O  or 
Th(SO4)2  •  4K2SO4  +  2H2O) .  Saturate  a  solution  of  a  thorium 
salt  with  potassium  sulphate.  (The  corresponding  sodium 
salt  (Th(SO4)2-Na2SO4  +  6H2O)  is  somewhat  soluble  in 
excess  of  sodium  sulphate.) 

Experiment  6.  Precipitation  of  thorium  phosphate, 
(Th3(PO4)4  +  4H2O).  To  a  solution  of  a  thorium  salt  add 
sodium  phosphate  in  solution.  Orthophosphoric  acid  is 
said  to  precipitate  an  acid  phosphate  (ThH2(P04)2). 

Experiment  7.  Precipitation  of  thorium  fluoride, 
(ThF4  +  4H2O).  To  a  solution  of  a  thorium  salt  add  a 
solution  of  potassium  fluoride.  Double  salts  with  thorium 
fluoride  may  also  form  (#KF-/ThF4  typical). 

Experiment  8.  Precipitation  of  thorium  ferrocyanide, 
(ThFe(CN)6  +  4H2O).  To  a  solution  of  a  thorium  salt  add 
a  solution  of  potassium  ferrocyanide.  Note  the  absence 
of  precipitation  with  potassium  ferricyanide. 

Experiment  9.  Action  of  hydrogen  peroxide  upon  salts 
of  thorium.  To  a  solution  of  a  thorium  salt  add  a  little 
hydrogen  peroxide,  and  warm. 

Experiment  10.  Negative  test  of  thorium  salts.  To  a 
solution  of  a  thorium  salt  add  hydrogen  sulphide.  Note 
that  ammonium  sulphide  precipitates  the  hydroxide,  not 
the  sulphide. 

V.  ZIRCONIUM,  Zr,  90.6. 

Discovery.  While  engaged  in  the  analysis  of  the  zircons, 
in  1788,  Klaproth  found  one  variety  containing  31.5%  of 
silica,  0.5%  of  the  oxides  of  iron  and  nickel,  and  68%  of  an 
earth  which  differed  from  all  earths  previously  known  to 
him.  He  observed  that  it  was  soluble  in  the  acids,  but 


76  THE  RARER  ELEMENTS. 

insoluble  in  the  alkalies,  in  the  latter  respect  differing  from 
alumina  (Ann.  de  Chim.  i,  238).  The  fact  that  zircon  was 
the  source  of  the  new  earth  suggested  the  name  Zirconium 
for  the  element. 

Occurrence.  Zirconium  is  found  combined,  widely  dif- 
fused, but  always  in  small  quantities  (vid.  Occurrence  of 
Rare  Earths,  page  35).  Its  chief  source  is  zircon. 

Extraction.  Zirconium  salts  may  be  extracted  from 
zircon  by  the  following  methods: 

(1)  The   finely   powdered   mineral   is   fused   with   acid 
potassium  fluoride   (vid.   Experiment   i)    (Marignac,   Ann. 
Chim.  Phys.  [3]  LX,  257). 

(2)  The   mineral   is   fused   with   potassium   bisulphate 
and  the  fused  mass  extracted  with  dilute  boiling  sulphuric 
acid.     The  basic  sulphate  (3Zr02-S03)  is  left  as  a  residue 
(Franz,  Ber.  Dtsch.  chem.  Ges.  n,  58). 

(3)  The  finely  powdered  mineral  is  heated  with  a  mix- 
ture of  sodium  hydroxide  and  sodium  fluoride,  the  mass 
is  cooled,  pulverized,  and  extracted  with  water.  The  residue, 
which  consists  mainly  of  sodium  zirconate,  is  digested  with 
hydrochloric  acid  until  dissolved.  After  the  solution  has 
been  evaporated  to  a  small  volume  the  zirconium  oxy- 
chloride  separates  in  crystalline  form  (Bailey,  Proc.  Royal 
Soc.  XLVI,  74). 

(4)  The  finely  powdered  mineral  is  fused  with  sodium  car- 
bonate, and  the  melt,  consisting  of  sodium  silicate  and 
sodium  zirconate,  is  extracted  with  water.  The  silicate 
dissolves  and  the  zirconate  is  hydrolyzed,  forming  zirco- 
nium hydroxide,  which,  after  washing,  is  dissolved  in  hydro- 
chloric or  sulphuric  acid. 

The  Element.  A.  Preparation.  Elementary  zirconium 
may  be  obtained  in  the  amorphous  condition  (i)  by  reducing 
potassium  fluozirconate  with  potassium  (Berzelius),  and  (2) 
by  reducing  the  oxide  with  magnesium  (Phipson) .  It  may 
be  obtained  in  crystalline  form  by  heating  potassium 


ZIRCON.  UM.  77 

fluozirconate  with  aluminum  (Troost),  and  in  graphitic 
form  by  heating  sodium  fluozirconate  with  iron  at 
850°  C. 

B.  Properties,  (i)  Zirconium  in  the  amorphous  con- 
dition is  a  black  powder.  Heated  in  the  air  it  burns  brightly 
to  the  oxide.  It  oxidizes  also  when  fused  with  alkali 
nitrates,  carbonates,  and  chlorates,  and  is  only  slightly 
attacked  by  acids. 

(2)  In  crystalline  form  zirconium  has  much  the  ap- 
pearance of  antimony.  Heated  in  the  air  it  oxidizes  very 
slowly.  It  is  not  acted  upon  by  fusion  with  alkali  nitrates, 
carbonates,  or  chlorates,  but  is  soluble  in  the  acids  upon 
the  application  of  heat.  Its  specific  gravity  is  4.15. 

Compounds.  A.  Typical  forms.  The  following  are 
typical  compounds  of  zirconium: 

Oxides,  ZrO2;  Zr03. 

Hydroxide,    Zr(OH)4. 

Chlorides,  ZrCl4 ;  also  double  salts  with  KC1  and  NaCl. 

Oxyhalides,  ZrOCl2+3H2O ;  ZrOBr2+3H2O;  ZrI(OH)3+3H2(X 

Bromide,  ZrBr4. 

Iodide,   ZrI4. 

Fluoride,   ZrF4. 

Oxysulphide,  ZrOS. 

Sulphite,  Zr(S03)2. 

Sulphates,   Zr(SO4)2  +  4H2O;  3ZrO2-SO3. 

Selenite,   Zr(SeO3)2. 

Nitrate,   Zr(NO3)4  +  sH2O. 

Phosphate,   Zr3(PO4)4. 

Pyrophosphate,   ZrP2O7. 

Carbonate,   3ZrO2-CO2  +  8H2O. 

Oxalates,   Zr(C2O4)2-2Zr(OH)4;   Zr(C2O4)2-K2C2O4.H2C2O4  + 

8H2O. 
Zirconates,  Na4ZrO4;  Li2ZrO3,  etc. 


78  THE  RARER  ELEMENTS. 

Zirconyl  *-nitric   or  nitrato-zirconic  acid, 

4H20. 
Zirconyl-sulphuric  or  sulphato-zirconic  acid,  H2ZrO(SO4)2  + 

3H20. 

Fluozirconate,  K2ZrF6. 
Carbide,  ZrC. 
Silicide,  ZrSi. 

B.  Characteristics.  In  chemical  structure  the  com- 
pounds of  zirconium  bear  a  strong  resemblance  to  those 
of  thorium,  titanium,  germanium,  and  silicon.  The  oxide, 
in  its  behavior  as  a  base  toward  oxides  having  more  acidic 
qualities,  resembles  the  oxide  of  thorium  (Th02).  With 
the  weaker  acids,  carbonic  and  oxalic,  it  shows  weaker 
basic  properties  in  the  formation  of  basic  salts.  With 
strong  bases  it  manifests  acidic  properties,  like  the  oxide 
of  titanium,  and  forms  zirconates  (vid.  Typical  Forms, 
above).  The  hydroxide  of  zirconium  is  insoluble  in  excess 
of  the  alkali  hydroxides,  the  double  sulphate  with  potas- 
sium is  insoluble  in  a  solution  of  potassium  sulphate,  and 
the  oxalate  is  soluble  in  ammonium  oxalate.  Solutions 
of  pure  zirconium  salts  are  said  to  give  no  precipitate  with 
hydrofluoric  acid  or  potassium  hydronitride.  Turmeric 
paper,  when  dipped  into  a  solution  of  a  zirconium  salt  and 
dried,  is  colored  orange. 

Estimation.  Zirconium  is  usually  weighed  as  the  oxide 
(ZrO2)  obtained  by  ignition  of  the  hydroxide  or  oxalate. 

Separation.  Zirconium,  with  the  other  rare  earths,  may 
be  roughly  separated  from  other  elements  by  the  action 
of  oxalic  acid  (vid.  page  48).  For  the  separation  from 
yttrium,  cerium,  and  thorium  see  under  those  elements. 
The  separation  of  zirconium  from  iron  and  titanium  has 

*  Rosenheim,  Ber.  Dtsch.  chem.  Ges.  XL,  803,  810;  Hauser,  Zeitsch.  anorg. 
Chem.  Lin,  74;  LIV,  196. 


EXPERIMENTAL   IVO^K  ON  ZIRCONIUM.  79 

received  a  good  deal  of  attention  from  chemists.  Some 
of  the  methods  that  have  been  suggested  follow. 

From  iron  zirconium  may  be  separated  (i)  by  the  action 
of  water  upon  an  ethereal  solution  of  the  chlorides, — the 
oxychloride  of  zirconium  being  precipitated  (Matthews, 
Jour.  Amer.  Chem.  Soc.  xx,  846) ;  (2)  by  the  action  of 
gaseous  hydrochloric  acid  and  chlorine  at  a  temperature  of 
about  200°  C.  upon  the  mixed  oxides, — the  ferric  chloride 
being  volatilized  (Havens  and  Way,  Amer.  Jour.  Sci.  [4] 
vm,  217);  (3)  by  treatment  with  phenylhydrazine, — the 
zirconium  being  precipitated  (Allen,  Jour.  Amer.  Chem. 
Soc.  xxv,  426) ;  (4)  by  the  action  of  sulphurous  acid 
on  neutral  solutions, — the  zirconium  being  precipitated 
(Baskerville,  Jour.  Amer.  Chem.  Soc.  xvi,  475). 

From  titanium  zirconium  may  be  separated  (i)  by 
boiling  a  solution  containing  the  two  elements  with  dilute 
sulphuric  and  acetic  acids, — titanic  acid  being  precipitated 
free  from  zirconium  (Streit  and  Franz,  J.  pr.  Chem.  cvm, 
75 ;  Zeitsch.  anal.  Chem.  ix,  388) ;  (2)  by  treating  solu- 
tions acid  with  sulphuric  or  hydrochloric  acid  with  zinc 
until  the  titanium  is  reduced  to  the  condition  of  the  sesqui- 
oxide,  and  then  adding  potassium  sulphate, — the  zirconium- 
potassium  sulphate  being  precipitated  (Pisani,  Compt. 
rend.  LVII,  298;  Chem.  News  x,  91,  218);  (3)  by  adding 
ammonium  hydroxide  to  a  boiling  hydrofluoric  acid  solu- 
tion of  the  salts, — the  titanic  acid  being  precipitated 
(Demarcay,  Compt.  rend,  c,  740;  J.  B.  (1885),  1929). 

EXPERIMENTAL    WORK    ON    ZIRCONIUM. 

Experiment  i.  Extraction  of  zirconium  salts  from 
zircon.  Fuse  5  grm.  of  finely  powdered  zircon  in  a  platinum 
or  nickel  crucible  with  about  15  grm.  of  acid  potassium 
fluoride.  Pulverize  the  fused  mass  and  extract  with  hot 


So  THE  RARER  ELEMENTS. 

water  containing  a  few  drops  of  hydrofluoric  acid.*  Filter 
immediately  through  a  rubber  funnel  into  a  rubber  beaker. 
As  the  nitrate  cools,  potassium  fluozirconate  crystallizes 
out.  It  may  be  purified  by  recrystallization. 

Experiment  2.  .Precipitation  of  zirconium  hydroxide, 
(Zr(OH)4).  (a)  To  a  solution  of  .a  zirconium  salt  add  potas- 
sium, sodium,  or  ammonium  hydroxide.  Note  the  insolu- 
bility in  excess.  (b)  To  a  solution  containing  zirconium  add 
sodium  thiosulphate  in  solution  and  boil. 

Experiment  3.  Precipitation  of  zirconium  carbonate, 
(3ZrO2-CO2  +  8H2O).  (a)  To  a  solution  of  a  zirconium 
salt  add  sodium  or  potassium  carbonate.  Note  the  partial 
solubility  in  excess. 

(b)  Use  ammonium  carbonate  as  the  precipitant.     Note 
the  solvent   action  of  an  excess  and  the  precipitation  of 
the  hydroxide  on  boiling. 

(c)  Try  the  action  of  the  common  acids  upon  separate 
portions  of  zirconium  carbonate. 

Experiment  4.  Precipitation  of  zirconium  oxalate, 
(Zr(C2O4)2-2Zr(OH)4).  (a)  To  a  solution  of  a  zirconium 
salt  add  a  solution  of  oxalic  acid.  Note  the  effect  of  an 
excess  in  the  cold  and  on  warming. 

(b)  Use  ammonium  oxalate  as  the  precipitant.  Note 
the  solvent  action  of  an  excess  and  the  reprecipitation  by 
ammonium  hydroxide. 

Experiment  5.  Precipitation  of  zirconium  phosphate \ 
(#ZrO2-;yP2O5,  basic).  To  a  solution  of  a  zirconium  salt 
add  sodium  phosphate.  Orthophosphoric  acid  precipi- 
tates the  normal  phosphate  (Zr3(PO4)4). 

Experiment  6.  Precipitation  of  zirconium  ferrocyanide, 
(ZrFeC6N6?).  To  a  solution  of  a  zirconium  salt  add  potas- 
sium ferrocyanide. 

*  Glass  or  porcelain  dishes  must   not    be  used  when    hydrofluoric  acid  is 
present. 


EXPERIMENTAL   1VOZK  ON  ZIRCONIUM.  81 

Experiment  7-  Action  of  zirconium  salts  upon  turmeric 
paper.  Dip  a  piece  of  turmeric  paper  into  a  solution  of  a 
zirconium  salt  acidified  with  hydrochloric  acid.  Dry  on  the 
side  of  a  test-tube  or  beaker,  as  in  testing  for  boric  acid. 
Note  the  yellowish-red  color. 

Experiment  8.  .  Negative  tests  of  zirconium  salts.  Note 
that  neither  hydrogen  sulphide  nor  potassium  fluoride  gives 
a  precipitate  with  zirconium  salts.  Ammonium  sulphide 
precipitates  the  hydroxide,  not  the  sulphide. 


CHAPTER  V. 

GALLIUM,  Ga,  70. 

Discovery.  In  1875  Lecoq  de  Boisbaudran,  who  had 
done  much  work  with  spectrum  analysis,  notified  the 
Academic  des  Sciences  of  his  discovery  of  a  new  element 
in  a  zinc-blende  from  the  mine  of  Pierrefitte  in  the  Pyre- 
nees, and  proposed  for  it  the  name  Gallium  (Compt.  rend. 
LXXXI,  493;  Chem.  News  xxxn,  159).  The  individu- 
ality of  the  new  body  was  distinctly  indicated  by  the 
spectroscope,  but  so  small  was  the  amount  of  it  in  the 
possession  of  the  discoverer  that  few  of  its  reactions  were 
determined.  Among  the  properties  which  he  described, 
however,  were  the  following:  the  oxide,  or  perhaps  a  sub- 
salt,  was  thrown  down  by  metallic  zinc  in  a  solution  con- 
taining chlorides  and  sulphates;  in  a  mixture  containing 
an  excess  of  zinc  chloride  the  new  body  was  the  first  to 
be  precipitated  by  ammonia;  in  the  presence  of  zinc  it 
was  concentrated  in  the  first  sulphides  deposited;  the 
spark  spectrum  of  the  concentrated  chloride  showed  two 
violet  lines,  one  of  them  of  considerable  brilliance. 

Occurrence.  Gallium  is  found  combined,  in  very  small 
amounts,  in  certain  minerals,  chiefly  zinc-blendes  from 
Bensberg  on  the  Rhine,  Pierrefitte,  and  other  localities. 
It  has  been  detected  in  some  American  zinc-blendes  (Chem. 
Ztg.  (1880),  443).  The  Bensberg  sphalerite,  one  of  the 
richest  sources,  contains  0.016  grm.  per  kilo. 

82 


GALLIUM.  83 

Hartley  and  Ramage  obtained  the  following  interesting 
results  by  means  of  the  spectroscope  (Jour.  London  Chem. 
Soc.  (1897),  533,  547) :  the  presence  of  gallium  was  indicated 
in  thirty -five  out  of  ninety -one  iron  ores  examined;  in  all 
the  magnetites,  seven  in  number;  in  all  the  aluminum 
ores,  fifteen  in  number,  mostly  kaolin  and  bauxite;  in 
four  out  of  twelve  manganese  ores;  and  in  twelve  out  of 
fourteen  zinc-blendes. 

Extraction.  Salts  of  gallium  are  obtained  by  the  fol- 
lowing process :  The  mineral  is  dissolved  in  aqua  regia  and 
the  excess  of  acid  expelled  by  boiling.  When  the  solution  is 
cold,  pure  zinc  is  added,  which  precipitates  the  antimony, 
arsenic,  bismuth,  copper,  cadmium,  gold,  lead,  mercury, 
silver,  tin,  selenium,  tellurium,  and  indium.  These  are 
filtered  off  while  there  is  still  some  evolution  of  hydrogen, 
and  the  filtrate  is  boiled  from  six  to  twenty-four  hours 
with  metallic  zinc.  Gallium  is  precipitated  as  a  basic 
salt,  together  with  salts  of  aluminum,  iron,  zinc,  etc.  To 
obtain  the  gallium  salt  in  a  more  nearly  pure  condition 
the  precipitate  is  dissolved  in  hydrochloric  acid,  the  solu- 
tion is  treated  with  hydrogen  sulphide,  and  after  filtra- 
tion and  the  removal  of  the  excess  of  hydrogen  sulphide 
by  boiling,  sodium  carbonate  is  added  in  small  portions. 
The  gallium  salt  is  the  first  to  be  precipitated,  and  the  pre- 
cipitates are  collected  as  long  as  they  show  the  gallium 
lines  in  the  spark  spectrum.  These  precipitates  are  dis- 
solved in  sulphuric  acid  and  the  solution  is  diluted  largely 
with  water  and  boiled.  The  basic  sulphate  of  gallium 
which  is  thus  thrown  down  is  dissolved  in  sulphuric  acid, 
and  potassium  hydroxide  is  added  in  excess.  Iron  if 
present  is  removed  at  this  point  by  filtration  and  the 
gallium  oxide  is  then  precipitated  from  the  filtrate  by 
carbon  dioxide. 

The  Element.  A.  Preparation.  Gallium  in  the  elemen- 
tary condition  has  been  obtained  by  subjecting  an  alkaline 
solution  of  the  oxide  to  electrolysis. 


84  THE  RARER   ELEMENTS. 

B.  Properties.  A  gray,  lustrous  metal,  showing  green- 
ish-blue lights  on  reflecting  surfaces,  gallium  is  malleable 
and  fairly  hard.  Its  fusing  point,  30.15°  C.,  is  so  low 
that  it  melts  readily  from  the  warmth  of  the  hand.  In 
water,  and  in  air  at  ordinary  temperatures,  it  is  unchanged ; 
when  heated  in  air  or  oxygen  it  is  oxidized  only  superfi- 
cially. It  combines  rapidly  with  chlorine,  more  slowly  with 
bromine,  and  not  at  all  with  iodine  unless  heat  is  applied. 
Gallium  is  soluble  in  hydrochloric  and  warm  nitric  acids, 
and  somewhat  soluble  in  potash  and  ammonia  solutions. 
It  alloys  easily  with  aluminum,  and  these  alloys  decompose 
cold"  water  rapidly.  Its  specific  gravity  is  6. 

Compounds.  A.  Typical  forms.  The  following  com- 
pounds of  gallium  are  known : 

Oxides .  .  GaO?  Ga2O3 

Hydroxide Ga(OH)3? 

Chlorides GaCl2  GaCl3 

Bromide GaBr3 

Iodide GaI3 

Nitrate Ga^NO^ 

Sulphate Ga2(SO4)3 

Double  sulphate Ga2(SO4)3  -  (NH4)2SO4  +  24H2O 

B.  Characteristics.  The  compounds  of  gallium  resem- 
ble those  of  aluminum  and  indium  in  forming  alums  and 
in  having  a  hydroxide  soluble  in  excess  of  sodium  or 
potassium  hydroxide.  The  salts  are  colorless,  and  in 
dilute  solutions  tend,  on  being  heated,  to  become  basic 
and  separate  from  the  solution.  The  oxide  (Ga2O3)  is  in- 
soluble in  acids  and  alkalies  after  ignition. 

Estimation.  Gallium  is  usually  weighed  as  the  oxide 
(Ga203). 

Separation.*     Vid.   Extraction. 

*  For  a  detailed  study  of  the  separation  of  gallium,  see  many  articles  by 
Lecoq  de  Boisbaudran,  Compt.  rend,  xciv-xcvm. 


INDIUM.  85 

INDIUM,  In.  115. 

Discovery.  Indium  was  discovered  by  Reich  and 
Richter  in  1863,  in  the  course  of  an  examination  of  two 
ores  consisting  mainly  of  the  sulphides  of  arsenic,  zinc, 
and  lead  (J.  pr.  Chem.  LXXXIX,  441).  These  ores  had  been 
freed  from  the  greater  part  of  their  arsenic  and  sulphur 
by  roasting,  and  the  residue  had  been  evaporated  to  dry- 
ness  with  hydrochloric  acid  and  distilled.  The  crude 
chloride  of  zinc  thus  obtained  was  examined  with  the 
spectroscope  for  thallium,  since  the  presence  of  that  element 
had  been  indicated  in  similar  ores  from  the  Freiberg  mines. 
Instead  of  the  thallium  line,  however,  appeared  one  of 
indigo  blue  never  before  observed.  The  color  suggested 
the  name  Indium  for  the  unknown  element  present. 

Occurrence.  Indium  occurs  in  very  small  amounts, 
combined  with  sulphur,  in  many  zinc-blendes.  It  has  been 
found  in  zinc-blende  from  Freiberg  and  Breitenbrun  in 
Saxony,  and  from  Schonfeld  in  Bohemia ;  in  christophite,  a 
variety  of  zinc-blende;  in  zinc  prepare'd  from  these  ores; 
and  in  the  flue-dust  from  ovens  used  for  roasting  zinc  ores. 
It  has  also  been  found  in  wolframite  from  Zinnwald.  The 
proportion  of  indium  in  the  minerals  named  varies  from 
one  tenth  of  one  per  cent,  to  mere  traces.  Lockyer  de- 
tected it  in  the  atmosphere  of  the  sun.  Hartley  and  Ra- 
mage  (Jour.  London  Chem.  Soc.  (1897),  533,  547)  have  dis- 
covered it  spectroscopically  in  many  iron  ores,— notably 
siderites, — in  some  manganese  ores,  in  zinc-blendes,  in 
five  tin  ores  examined,  and  in  many  pyrites. 

Extraction.  Indium  salts  may  be  obtained  as  follows 
from  zinc  that  has  been  extracted  from  indium-bearing 
blendes.  The  crude  metal  is  nearly  dissolved  in  hydro- 
chloric or  nitric  acid,  and  the  solution  is  allowed  to  stand 
twenty -four  hours  with  the  undissolved  metal.  A  spongy 


OF  THE 

UNIVERSITY  ) 

OF 
r*»  ,  , 


86  THE  R4RER  ELEMENTS. 

mass,  consisting  of  the  indium  together  with  lead,  copper, 
cadmium,  tin,  arsenic,  and  iron,  collects  upon  the  residual 
zinc.  This  mass  is  washed  with  water  containing  some 
sulphuric  acid ;  it  is  then  dissolved  in  nitric  acid  and  evapo- 
rated with  sulphuric  acid  until  all  the  nitric  acid  is  removed. 
By  this  process  the  lead  is  precipitated,  and  it  may  be 
removed  by  nitration.  The  solution  that  remains  is  treated 
with  ammonium  hydroxide  in  excess,  and  the  hydroxides 
of  iron  and  indium  are  filtered  off  and  dissolved  in  a  small 
amount  of  hydrochloric  acid.  This  solution  is  treated 
with  an  excess  of  acid  sodium  sulphite  and  boiled.  In- 
dium is  precipitated  as  the  basic  sulphite  (In2(SO3)s  •  In2(OH)a 
-f  5H2O).  Indium  may  also  be  separated  from  iron  by 
treating  the  chlorides  with  potassium  sulphocyanide  and 
extracting  the  ferric  sulphocyanide  with  ether.  Again,  it 
may  be  separated  from  aluminum  and  iron  by  treating 
the  chlorides  in  alcoholic  solution  with  pyridine.  The 
indium  is  precipitated  as  a  compound  of  indium  chloride 
and  pyridine  (InCl3-3C5H5N)  (Dennis,  Ber.  Dtsch.  chem. 
Ges.  xxxvn,  961 ;  Renz,  ibid,  xxxvn,  2110;  Mathers,  Jour. 
Amer.  Chem.  Soc.  xxx,  209). 

The  Element.  A.  Preparation.  Elementary  indium 
may  be  obtained  (i)  by  heating  the  oxide  with  carbon  or 
in  a  current  of  hydrogen;  (2)  by  heating  the  oxide  with 
sodium  under  a  layer  of  dry  sodium  chloride ;  (3)  by  treat- 
ing the  salts  with  zinc;  (4)  by  electrolyzing  the  sulphate 
in  the  presence  of  formic  acid  (Dennis) . 

B.  Properties.  Indium  is  a  soft  white  metal,  less  vola- 
tile than  cadmium  and  zinc.  It  melts  at  174°  C.  At 
ordinary  temperatures  it  is  stable  in  the  air,  but  when 
heated  it  ignites  and  burns  with  a  violet  flame  to  the 
oxide.  It  does  not  decompose  boiling  water.  It  dissolves 
easily  in  hydrochloric,  nitric,  and  sulphuric  acids.  It 
forms  alloys  with  lead  and  thallium.  Its  specific  gravity 
is  given  at  from  7.1  to  7.4. 


IND'UM.  87 

Compounds.*     A.   Typical  forms.     The  following  com- 
pounds of  indium  are  known: 

Oxides  .............  InO  ;  In2O3 

Hydroxide  ..........  In(OH)3 

Fluoride  ............  InF3  +  3H2O 

Chlorides  ...........  InCl  ;  InCl2  ;  InCl3 

Oxychloride  ........  InOCl 

Indium  -  hydrochloric 

acid  .............  H3InCl6 

Bromide  ...........  InBr3 

Iodide  .............  InI3 

Nitrate  ............  In2(NO3)6  +  9H2O 

Sulphate  ...........  In2(SO4)3 

Double  sulphates  ....  In2(SO4)3  •  K2SO4  +  24H2O  ; 

In2(S04)3-(NH4)2S04  + 


Sulphite  ............  In2(S03)3  -  In2(OH)6  +  5H2O 

Sulphides  ...........  In2S  ;  InS  ;    In2Sa 

Sulpho  salts  .........  K2In2S4  ;  Na2In2S4 

B.  Characteristics.  Indium  resembles  aluminum  in 
forming  alums  with  potassium  and  ammonium  sulphates,. 
and  in  having  a  hydroxide  soluble  in  excess  of  potassium 
or  sodium  hydroxide.  It  resembles  zinc  in  forming  a 
sulphide  with  hydrogen  sulphide,  but  in  the  case  of  indium 
this  salt  is  yellow.  Indium  monoxide  is  a  dark  powder 
slowly  soluble  in  dilute  acids.  The  sesquioxide  is  a  yellow- 
ish-white powder  easily  soluble  in  warm  acid  and  more 
infusible  than  aluminum  oxide.  The  dichloride  is  formed 
directly  by  the  union  of  chlorine  with  the  metal,  and  is  a 
white,  crystalline  mass.  In  water  it  separates  into  the 
trichloride  and  the  metal.  By  fusion  of  the  dichloride 

*  The  following  references  will  be  found  helpful:  Thiel,  Zeitsch.  anorg.  Chem. 
XL,  280;  Mathers,  Jour.  Amer.  Chem.  Soc.  xxix,  4^5;  xxx,  86,  21  r. 


88  THE  RARER  ELEMENTS. 

with  elementary  indium  the  monochloride  is  formed, — a 
reddish-bla:k,  crystalline  substance.  The  trichloride  is 
formed  also  by  the  action  of  chlorine  in  excess  upon  the 
metal ;  it  is  white  like  the  dichloride  and  dissolves  in  water 
with  the  evolution  of  heat.  Solutions  of  indium  salts  color 
the  flame  violet  and  give  a  characteristic  flame  spectrum. 

Estimation.  Indium  is  generally  determined  as  the 
oxide,  (I^Os),  obtained  by  ignition  of  the  hydroxide,  or  as 
the  sulphide,  (In2S3),  obtained  by  precipitation  with  hydro- 
gen sulphide  in  the  presence  of  sodium  acetate. 

Separation.  The  separation  of  this  very  rare  element 
from  those  elements  with  which  it  is  usually  associated  is 
treated  under  Extraction. 


THALLIUM,  Tl,  204.1. 

Discovery.  Some  years  previous  to  1861  Crookes  had 
been  engaged  in  the  extraction  of  selenium  from  a  selen- 
iferous  deposit  which  he  had  obtained  from  the  sulphuric- 
acid  manufactory  at  Tilkerode  in  the  Hartz  Mountains. 
Some  residues,  left  after  the  purification  of  the  selenium, 
and  supposed  to  contain  tellurium,  were  set  aside  and 
not  examined  until  1861,  when,  needing  tellurium,  Crookes 
vainly  tried  to  isolate  it  by  various  chemical  methods. 
At  length  he  resorted  to  spectrum  analysis  and  tested 
some  of  the  residue  in  the  flame.  The  spectrum  of  selen- 
ium appeared,  and  as  it  was  fading,  and  he  was  looking  for 
evidence  of  tellurium,  a  new  bright -green  line  flashed  into 
view.  The  element  whose  presence  was  thus  indicated 
received  the  name  Thallium,  from  the  Greek  BatXkos,  or 
the  Latin  thallus,  a  budding  twig  (Chem.  News  in,  194). 

About  the  same  time  Lamy  announced  the  discovery 
of  the  same  element  (Ann.  Chim.  Phys.  [3]  LXVII,  385), 
but  after  much  discussion  and  the  presentation  of  much 


THALLIUM.  89 

evidence  on  both  sides  it  was  declared  that  Crookes  had 
the  priority  of  discovery. 

Occurrence.  Thallium  occurs  in  certain  very  rare 
minerals : 

Crookesite,  (Cu,Tl,Ag)2Se  contains  16-19%  Tl 
Lorandite,  TlAsS2,  "        59-60%  Tl 

Hutchinsonite,  (Tl.Ag,Cu)2S'As2S34-PbS-As2S3,   contains 
18-25%  Tl 

It  is  found  also  in  very  small  quantities  in  berzelianite, 
(Cu2Se) ;  in  some  zinc-blendes  and  copper  pyrites ;  in  iron 
pyrites  from  Theux,  Namur,  Philippe ville,  Alais,  and  Nantes ; 
in  lepidolite  from  Mahren;  and  in  mica  from  Zinnwald. 
It  has  been  detected,  together  with  caesium,  rubidium,  and 
potassium,  in  the  mineral  waters  of  Nauheim  and  Orb. 
Its  presence  in  the  flue -dust  from  some  iron  furnaces  and 
sulphuric -acid  works,  as  well  as  in  some  crude  sulphuric 
and  hydrochloric  acids,  may  be  traced  to  its  presence  in 
the  pyrites  used. 

Extraction.  Thallium  salts  may  be  extracted  by  the 
following  methods: 

(1)  From  minerals.  The  finely  powdered  mineral  is  dis- 
solved in  aqua  regia.     The   solution  is  evaporated  with 
sulphuric  acid  until  the  free  acid  has  been  removed ;  it  is 
then    diluted    abundantly    with    water,    neutralized    with 
sodium  carbonate,   and  treated  with  potassium  cyanide 
in  excess.     This  precipitates  the  bismuth  and  lead,  which 
are   filtered   off.     The   filtrate   is   treated   with   hydrogen 
sulphide,  which  precipitates  the  cadmium,  mercury,  and 
thallium   as   the    sulphides.     Very    dilute    sulphuric    acid 
dissolves  the  thallium  sulphide,  leaving  the  cadmium  and 
mercury  sulphides  undissolved  (Crookes). 

(2)  From  flue-dust.      The  material  is  treated  with  an 
equal  weight  of  boiling  water  in  a  large  wooden  tub,  and  is 
allowed   to    stand   twenty-four   hours.     The   liquid   is   si- 


90  THE   RARER   ELEMENTS. 

phoned  off  and  is  precipitated  with  hydrochloric  acid.* 
The  crude  chloride  thus  obtained  is  treated  with  an  equal 
weight  of  sulphuric  acid,  and  heated  to  expel  the  hydro- 
chloric acid  and  the  greater  part  of  the  excess  of  sulphuric. 
The  sulphate  obtained  is  dissolved  in  water,  the  solution 
is  neutralized  with  chalk  and  filtered.  By  the  addition 
of  hydrochloric  acid  to  the  filtrate,  nearly  pure  thallous 
chloride  is  precipitated  (Chem.  News  vm,  159). 

The  Element.  A.  Preparation.  The  element  thallium 
may  be  obtained  (i)  by  fusing  a  mixture  of  thallous  chloride 
and  sodium  carbonate  with  potassium  cyanide;  (2)  by 
submitting  the  carbonate  or  the  sulphate  to  electrolysis; 
(3)  by  heating  the  oxalate;  and  (4)  by  precipitating  with 
zinc  from  an  alkaline  solution  of  a  thallous  salt. 

B.  Properties.  Metallic  thallium  is  in  color  whitish 
to  blue  gray,  with  the  luster  of  lead.  It  is  soft  and  malle- 
able and  melts  at  285°  C.  It  forms  alloys  with  many  of 
the  metals  (Kurnakow,  Zeitsch.  anorg,  Chem.  xxx,  86 ;  LIT, 
430).  It  oxidizes  readily  at  high  temperatures,  but  is  not 
acted  upon  by  water  free  from  air.  It  is  soluble  in  dilute 
nitric  and  sulphuric  acids.  It  is  a  poor  conductor  of  elec- 
tricity. The  specific  gravity  of  thallium  is  n.88. 

Compounds/)-  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  thallium: 

Oxides T12O  T12O3 

Hydroxides T1OH  Tl(OH), 

Carbonate T12CO8 

Chlorides T1C1  T1C13+  H2O 

Double  chlorides . .  T1C1  -  HgCl2 ;  3T1C1  •  FeCl, ;  T1C1,  -  3KC1+  2H,O ;  etc. 

TlCl-AuCls;  etc. 

Chlorate.. T1C1O, 

Perchlorate T1C1O4 

*  Three  tons  of  dust  gave  sixty-eight  pounds  of  crude  thallous  chloride. 
fSee  also  Hawley,  Jour.  Amer.  Chem.  Soc.  xxix,  300,  ion;    Stortenbeker, 
Rec.  trav.  chim.  Pays-Bas,  xxvi,  248;  Thomas,  Ann.  chim.  phys.  xi  [8],  204. 


THALLIUM.  91 

Bromides TlBr  TIBr, 

Double  bromides . .  TIBr,  •  KBr+  2H,O ; 

TlBr,-3TlBr 

Bromate TIBrO, 

Iodides Til  Til, 

Double  iodides Til  •  KI  Til,  •  NH4I 

lodates T1IO,  T1(IO,)S 

Periodate 3T12O,  •  I,O7+  3oH,O 

Thiosulphate T12S2O, 

Sulphides T12S  T12S, 

Sulphite T12SO, 

Sulphates T12SO4;  T1HSO4  TljCSOJ, 

Double  sulphates. .  with  MgSO4,  ZnSO4,  CuSO4, etc. 

Alums T12S(V  A12(S04)3+  24H2O; 

Tl2S04.Fe2(S04)3-f24H20 

Nitrates T1NO8  T1(NO3)3+  4H3O 

Phosphates T1,PO4;  T14P2O7;  T1POS  T1PO4+  2H2O 

Arseniates Tl3AsO4  TlAsO4+  2H2O 

Cyanides T1CN  T1(CN)3  -  T1CN 

Sulphocyanide T1SCN 

Ferrocyanide Tl4Fe(CN)8+  2H,O 

Silicofluoride TIaSiF,, 

Chromates Tl2CrO4;  Tl2Cr2O7 

Chloroplatinate  . . .  Tl2PtCl8 

Molybdate Tl2MoO4 

Tungstate T12WO4 

Vanadates T13VO4;  T14V2O7;  T1VO3 

B.  Characteristics.  Thallium  compounds  are  known 
in  two  conditions  of  oxidation,  the  thallous,  (T12O),  and 
the  thallic,  (T12O3) .  The  lower  condition  is  the  more  stable ; 
consequently  the  thallous  compounds  are  the  more  numer- 
ous and  the  better  known.  When  the  metal  is  allowed 
to  oxidize  in  the  air  it  forms  the  thallous  oxide,  but  when  it 
is  melted  in  an  atmosphere  of  oxygen,  thallic  oxide  is  ob- 
tained. Thallic  chloride,  bromide,  and  iodide  may  be 
formed  by  treating  the  corresponding  thallous  salts  with 
an  excess  of  chlorine,  bromine,  and  iodine,  respectively. 
In  general,  the  thallous  salts  may  be  oxidized  to  the  thallic 
form  by  strong  oxidizing  agents,  such  as  potassium  per- 
manganate, lead  dioxide,  barium  dioxide,  etc.  Thallium 
in  the  lower  condition  resembles  the  alkalies  potassium, 


92  THE  RARER  ELEMENTS. 

caesium,  and  rubidium  in  having  a  soluble  hydroxide,  car- 
bonate, and  sulphate,  and  an  insoluble  chloroplatinate  and 
cobaltic  nitrite;  also  in  forming  alums.  It  resembles  lead 
in  forming  an  insoluble  sulphide  and  chromate,  and  in 
having  halogen  salts  soluble  in  hot  water.  The  thallous 
salts  are  colorless  when  the  base  is  combined  with  a  color- 
less acid.  The  sulphide  is  brownish  black.  The  thallic 
salts  are  in  general  unstable,  and  on  being  heated  with 
water  tend  to  precipitate  the  oxide  (T12O3-H2O).  They 
may  be  easily  reduced  to  the  lower  condition  by  the  action 
of  reducing  agents.  They  may  be  formed  by  the  careful 
treatment  of  thallic  oxide  with  acids  as  well  as  by  the 
action  of  strong  oxidizing  agents  upon  the  thallous  salts. 
Solutions  of  thallium  salts  in  either  condition  of  oxidation 
give  to  the  flame  a  characteristic  green  color. 

Estimation.*  A.  Gravimetric.  Thallium  is  generally 
weighed  in  the  thallous  condition  (i)  as  the  chloroplati- 
nate, (Tl2PtCl6) ,  after  precipitation  by  chloroplatinic  acid 
(Crookes,  Select  Methods,  Second  Edition,  380) ;  (2)  as  the 
iodide  (Til),  after  precipitation  by  potassium  iodide 
(Werther,  Zeitsch.  anal.  Chem.  in,  i,  and  J.  B.  (1864),  712; 
Long,  Zeitsch.  anal.  Chem.  xxx,  342) ;  (3)  as  the  chro- 
mate (Tl2CrO4),  after  precipitation  in  alkaline  solution  by 
potassium  chromate  (Browning  and  Hutchins,  Amer. 
Jour.  Sci.  [4]  vm,  460);  (4)  as  the  sulphate  (T12SO4),  after 
evaporation  of  appropriate  salts  with  sulphuric  acid  in  ex- 
cess and  ignition  at  low  red  heat,  or  as  the  acid  sulphate, 
(T1HSO4),  obtained  by  substituting  for  ignition  heating  at 
22o°-24o°  C.  (Browning,  Amer.  Jour.  Sci.  [4]  ix,  137).  It 
may  be  estimated  also  by  weighing  the  gold  precipitated 

*  See  also  Hebberling,  Liebig  Annal.  cxxxv,  207;  Phipson,  Compt.  rend, 
xxvm,  563;  Neumann,  Liebig  Annal.  CCXLIV,  349;  Feit,  Zeitsch.  anal.  Chem. 
xxvin,  314;  Carnot,  Compt.  rend,  cix,  177;  Sponholz,  Zeitsch.  anal.  Chem. 
xxxi,  519;  Thomas,  Compt.  rend,  cxxx,  1316;  Marshall,  Jour.  Soc.  Chem.  Ind. 
xix,  994. 


EXPERIMENTAL    WORK   ON  THALLIUM.  93 


according  to  the  equation:  3TlCl+2AuBr3  = 
(Thomas,  Ann.  chim.  phys.  xi  [8],  204). 

B.  Volumetric.  Thallium  is  estimated  volumetric- 
ally  (i)  by  the  oxidation  of  thallous  salts  with  perman- 
ganate (Crookes,  Select  Methods,  Second  Edition,  381)  ; 
(2)  by  the  action  of  potassium  iodide  upon  thallic  salts, 
as  shown  in  the  following  equation  (Thomas,  Compt.  rend. 
cxxxiv,  655):  T1C13  +  3KI=T1I  +  3KC13  +  I2. 

Separation.*  In  the  more  stable  thallous  condition,  to 
which  thallic  salts  may  readily  be  reduced,  thallium  may 
be  separated  as  follows:  from  the  metals  which  give 
precipitates  with  hydrogen  sulphide  in  acid  (but  not  acetic) 
solution,  by  hydrogen  sulphide;  from  elements  which 
form  insoluble  hydroxides  with  the  alkali  hydroxides,  by 
these  reagents;  and  from  the  alkalies  and  alkali  earths, 
by  ammonium  sulphide. 


EXPERIMENTAL  WORK  ON  THALLIUM. 

Experiment  i.  Extraction  of  thallium  salts  from  flue~ 
dust.  The  method  described  under  Extraction  may  be 
followed. 

Experiment  2.  Precipitation  of  thallous  chloride,  bro- 
mide, and  iodide  (T1C1;  TIBr;  Til),  (a)  To  a  solution  of 
a  thallous  salt  add  hydrochloric  acid  or  a  chloride  in  solu- 
tion. Note  the  solvent  action  of  boiling  water.  Try 
the  effect  of  cooling  the  hot  solution. 

(b)  Repeat  the  experiment,  using  potassium  bromide 
as  the  precipitant. 

(c)  Try  similarly  potassium  iodide. 

Experiment  3.  Precipitation  of  thallium  chloroplati- 
nate  (Tl2PtG6).  To  a  solution  of  .a  thallous  salt  add  a 
few  drops  of  a  solution  of  chloroplatinic  acid. 

*  See  Crookes,  Select  Methods,  Second  Edition,  382-386. 


94  THE  R4RER  ELEMENTS. 

Experiment  4.  Precipitation  of  thallium  cobaltic  nitrite. 
To  a  solution  of  a  thallous  salt  add  a  few  drops  of  a  solu- 
tion of  sodium  cobaltic  nitrite. 

Experiment  5.  Precipitation  of  thallous  chr  ornate 
(Tl2CrO4).  To  a  solution  of  a  thallous  salt  add  some  potas- 
sium chromate  in  solution.  Try  the  action  of  acids  upon 
the  precipitate. 

Experiment  6.  Precipitation  of  thallous  sulphide  (T12S). 
(a)  Through  a  solution  of  a  thallous  salt  acidified  with 
dilute  sulphuric  acid  pass  hydrogen  sulphide.  Note  the 
absence  of  precipitation.  Divide  the  solution,  and  to  one 
part  add  ammonium  acetate  and  to  the  other  ammonium 
hydroxide. 

(b)  Try  the  action  of  ammonium  sulphide  upon  a  thal- 
lous salt  in  solution. 

Experiment  7.  Oxidation  of  thallous  salts.  (a)  To 
a  solution  of  a  thallous  salt  acidified  with  sulphuric 
acid  add  gradually  a  little  potassium  permanganate. 
Note  the  disappearance  of  the  color  of  the  perman- 
ganate. 

(b)  To  a  solution  of  a  thallous  salt  add  bromine 
water  until  the  color  of  the  bromine  ceases  to  fade. 
To  one  portion  add  a  few  drops  of  a  solution  of  a 
chloride  or  bromide.  Note  the  absence  of  precipitation. 
To  another  portion  add  sodium  or  potassium  hydroxide. 
Note  the  precipitation  of  brown  thallic  hydroxide, 
(T1203-H20). 

Experiment  8.  Reduction  of  a  thallic  salt.  To  a  solution 
of  a  thallic  salt  formed,  for  example,  as  in  Experiment 
7  (b)  add  stannous  chloride.  Note  the  precipitation 
cf  thallous  chloride,  (T1C1). 

Experiment  9.  Flame  and  spectroscopic  tests  for  thal- 
lium salts,  (a)  Dip  the  end  of  a  platinum  wire  into  a 
solution  of  a  thallium  salt  and  hold  it  in  the  flame  of  a 
Bunsen  burner.  Note  the  green  color. 


EXPERIMENTAL    WORK  ON  THALLIUM.  95 

(6)  Examine  spectroscopically  the  flame  colored  by  a 
solution  of  a  thallium  salt.  Observe  the  green  line. 

Experiment  10.  Negative  tests  of  thallous  salts.  Note 
that  sulphuric  acid  and  the  alkali  hydroxides  and  car- 
bonates give  no  precipitate  with  solutions  of  thallous  salts. 


CHAPTER  VI. 


TITANIUM,  Ti,  48.1. 

Discovery.  In  the  year  1791  McGregor  (Crell  Annal.  (1791) 
I,  40,  103)  discovered  a  new  ''metal"  in  a  magnetic  sand 
found  in  Menachan,  Cornwall.  This  sand  he  named  Mena- 
chinite,  and  the  newly  discovered  element  Menachite.  Four 
years  later  Klaproth  announced  the  discovery  of  a  new  earth 
in  a  rutile  which  he  was  engaged  in  studying  (Klapr.  Beitr. 
I,  233).  To  the  metal  of  this  earth  he  gave  the  name  Tita- 
nium, in  allusion  to  the  Titans.  In  1797,  however,  he 
found  that  titanium  was  identical  with  menachite  (Klapr. 
Beitr.  n,  236). 

Occurrence.  Titanium  is  found  combined  in  many 
minerals,  but  never  in  considerable  quantity  in  any  one 
locality. 

Contains  TiOa 

Rutile,  Ti02 90-100% 

Dicksbergite,  vid.  Rutile 90-100% 

Brookile,  Ti02 90-100% 

Octahedrite,  TiO2 90-100% 

Pseudobrookite,  Fe4(TiO4)3 44-  53% 

Perofskite,  CaTiO3 58-  59% 

llmenite,  FeTiO3 3-  59% 

Magnetite,  FeO-Fe2O3 o-    6% 

Geikielite,  MgO-TiO2 67-  68% 

Senaite,  (Fe,Pb)O-2(Ti,Mn)O2 57-  58% 

96 


TITANIUM.  97 

Zirkelite,  (Ca,Fe)O-2(Zr,Ti,Th)O,  ..............  14-15% 

Knopite,  R0-Ti02:  ..........................  54~  59% 

Derbylite,  6FeO  -  5TiO2  •  Sb2O5.  .  ...............  34-  35% 

Lewisite,  sCaO-2TiO2-3Sb2O5  .................  n-  12% 

Mauzeliite,  4(Ca,Pb)0  -TiO2  -  2Sb2O5  ............  7-     8% 

Titanite,  CaTiSiO5  ...........................  34-  42  % 


Neptunite,  R2RTiSi4O12  .......................  17-  18% 

Hainite,  formula  doubtful  .................   undetermined 

Lamprophyllite,  formula  doubtful  .......... 

Keilhauite,  complex  silicate  ...................  26-  36% 

Schlormenite,  3CaO(Fe,Ti)2O3-3(Si,Ti)O2  ........  12-  22% 

Guarinite,  CaTiSiO5  ..........................  33~  34% 

Tscheffkinite,  complex  silicates  ................  16-  21  % 

Astrophyllite,  (Na,K)4(Fe,Mn)4Ti(SiO4)4  ........  7-  14% 

Johnstrupite,  complex  silicates  ................  7-     8% 

Mosandrite,                         "       ................  5-  10% 

Rinkite,                 "              "       ................  13-  14% 

Dysanalyte,  6(Ca,Fe)TiO3-  (Ca,Fe)Nb2Ofl  ........  40-  59% 

Pyrochlore,  RNb2O6-R(Ti,Th)O3,  ..............  5-  14% 


in  in 


^schynite,  R2Nb4O13-R2(Ti,Th)5O13  ............    21-  22% 

Polymignite,  5RTiO3-5RZr03-R(Nb,Ta)2O6  .....    18-  19% 

Yttrocrasite,  complex  titanite  ..................   49-  50% 

Marignacite,  vid.  Pyrochlore  ...................     2-     3% 

in  in 

Euxenite,  R(NbO3)  3  -R2(TiO3)3-tH20  ...........  20-  23% 

in  in 

Polycrase,  R(NbO3)3-2R(Ti03)3-3H20  ..........   25-  29% 

Yttro  titanite  vid.  Keilhauite. 

Titanium  has  been  found  also  in  sand  on  the  banks  of  the 
North  Sea,  in  some  mineral  waters,  in  certain  varieties  of 
coal,  in  meteorites,  and  by  means  of  the  spectroscope  it 
has  been  detected  in  the  atmosphere  of  the  sun.  It  has 
been  found  in  the  ash  of  oak,  apple,  and  pear  wood,  in 
cow  peas,  in  cotton-seed  meal,  and  in  the  bones  of  men 


98  THE  RARER  ELEMENTS. 

and  animals.     Vid.  also    Basket ville,  Jour.  Amer.  Chem, 
Soc.  xxi,  1099. 

Extraction.      Titanium    salts    may   be    extracted    from 
rutile  by  the  following  methods: 

(1)  The  mineral  is  fused  with  three  parts  of  a  mixture 
of  sodium  and  potassium  carbonates  and  the  fused  mass 
is  extracted  with  water.     The  titanium,  as  a  sodium  or 
potassium  titanate,  remains,  together  with  some  tin  and 
iron,  in  the  insoluble  residue.     This  mass  is  treated  with 
strong  hydrochloric  acid  until  dissolved.     The  solution  is 
then  diluted,  and  the  tin  is  removed  by  hydrogen  sulphide. 
The  sulphide  of  tin  is  filtered  off,  the  filtrate  is  made  am- 
moniacal  with  ammonium  hydroxide   and   again   treated 
with  hydrogen  sulphide.     The  iron  is  precipitated  as  the 
sulphide,  and  the  titanium  as  the  hydroxide.     After  filtra- 
tion the  precipitate  is  suspended  in  water  and  a  current 
of  sulphur  dioxide  is  passed  through  until  the  black  sul- 
phide of  iron  has  dissolved,  leaving  the  oxide  of  titanium. 

(2)  The  mineral  is  fused  with  three  parts  of  acid  potas- 
sium fluoride  and  the  fused  mass  is  extracted  with  hot  water 
and  a  little  hydrofluoric  ^acid.     The  titanium  separates,  on 
cooling,  as  the  potassium  fluotitanate  (K2TiF6  +  H2O). 

(3)  The  mineral,  finely  pulverized,  is  fused  with  three 
times  its  weight  of  sodium  dioxide  and  the  melt  is  extracted 
with  water.     The  titanium   remains   in   solution    (H.   D. 
Newton) . 

(4)  The  mineral  is  fused  with  six  parts  of  acid  potassium 
sulphate  (vid.  Experiment  i). 

(5)  The  mineral  is  mixed  with  carbon  and  heated  in 
the  electric  furnace.    The  carbide  thus  formed  is  converted 
into  the  chloride  by  heating  it  with  dry  chlorine  (Stabler, 
Ber.  Dtsch.  chem.  Ges.  xxxvm,  2619). 

(6)  The  mineral  is  heated  to  1000°  and  chilled  in  water. 
The  powder  is  mixed  with  aluminum  (one  half  its  weight) 
and  ignited  by  burning  magnesium.     On  heating  the  metal 


TITANIUM. 


99- 


obtained  to  a  red  heat  in  a  current  of  dry  chlorine  titanium 
tetrachloride  distils  (Ellis,  Chem.  News,  xcv,  122). 

The  Element.  A.  Preparation.  Elementary  titanium 
may  be  obtained  (i)  by  heating  potassium  fluotitanate 
with  potassium  (Berzelius  and  Wohler)  ;  (2)  by  passing 
the  vapor  of  the  chloride  (TiCl4)  through  a  bulb  tube  con- 
taining sodium. 

B.  Properties.  As  prepared  in  the  laboratory,  tita- 
nium is  a  dark-gray  powder.  It  does  not  decompose  water 
at  ordinary  temperatures  and  acts  on  heated  water  but 
slightly.  When  heated  in  the  air  it  combines  with  the 
oxygen,  burning  brightly  to  the  oxide  (TiO2)  ;  in  oxygen 
the  combination  is  accompanied  with  brilliant  light.  Ti- 
tanium is  readily  soluble  in  warm  hydrochloric  acid,  and 
is  attacked  by  dilute  hydrofluoric,  nitric,  sulphuric,  and 
acetic  acids.  It  combines  with  chlorine.  It  combines  also- 
with  nitrogen,  forming  nitrides. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  titanium: 


Oxides  .  .  .  TiO  ;  (Ti3O4)  ;  Ti2O3  ; 
Hydroxides 

Chlorides  .  .  TiQ3 

Bromide... 
Iodide  ..... 
Fluoride  .  .  . 
Titanofluor- 
ides  ..... 

Sulphides  .  .  Ti2Ss 

Sulphates  .  .  T 

Nitrides  .  .  . 
Carbide  .  .  . 
Silicide  ____ 

Titanates... 

Acids  (vid.  Hydroxides)  .  .  . 


;  TiO2  ;  (Ti2O5)  ;  TiO3 
Ti(OH)4        Ti(OH)8 
TiCl4 
TiBr4 
TiI4 
TiF4 

R2TiF6,  etc. 
TiS2 

Ti(SO4)2 

Ti3N4;  Ti6N6;  TiN2 
TiC 
TiSi 

RTiO3;  R2TiO8 
H2TiO3 


300  THE  R4RER  ELEMENTS 

B.  Characteristics.  Although  a  number  of  oxides  of 
titanium  are  known,  the  dioxide  is  the  form  generally 
found,  and  the  salts  of  that  type  are  by  far  the  most  numer- 
ous and  important.  The  oxide  (TiO2)  resembles  the  oxide 
of  zirconium  (ZrO2)  in  acting  as  a  weak  base.  It  forms 
salts  with  the  strong  acids,  but  does  not  combine  with  the 

weak  acids.     It  unites  with  the  strong  bases  to  form  tita- 

ii  i 

nates,   (RTiO3  and  R2TiO3).     It  has  less  basic  and  more 

acidic  properties  than  the  oxide  of  zirconium.  The  tet- 
rachloride  is  a  colorless  liquid  which  fumes  in  the  air. 
Titanium,  in  its  behavior  toward  reagents,  resembles  quite 
closely  both  niobium  and  tantalum,  with  which  it  is  often 
found  associated  (vid.  Occurrence). 

Estimation.*  A.  Gravimetric.  Titanium  is  usually  pre- 
cipitated as  the  acid,  either  by  ammonium  hydroxide 
or  by  boiling  a  dilute  solution  acidified  with  acetic  or 
sulphuric  acid ;  the  precipitate  is  ignited  and  the  element 
is  determined  as  the  oxide  (TiO2). 

B.  Volumetric.  Titanium  is  estimated  volumetrically 
(i)  by  treating  with  hydrogen  dioxide  a  definite  amount 
of  the  titanium  solution  to  be  determined  and  com- 
paring its  color  with  that  of  a  definite  amount  of  a 
standard  solution  of  titanium  similarly  treated  (Weller, 
Ber.  Dtsch.  chem.  Ges.  xv,  2592);  (2)  by  reducing  the 
titanium  from  the  dioxide  to  the  sesquioxide  condition, 
by  the  use  of  zinc  and  hydrochloric  acid,  and  then  oxidiz- 
ing it  with  permanganate  (Osborn,  Amer.  Jour.  Sci.  [3] 
xxx,  329);  (3)  by  reducing  the  titanium  from  the  dioxide 
to  the  sesquioxide  condition  in  an  atmosphere  of  hydro- 
gen, by  means  of  zinc  and  sulphuric  acid,  then  oxidizing  it 
by  an  excess  of  a  ferric  salt,  and  estimating  the  titanium 

*  For  estimation  in  ores  see  Technical  Methods  of  Ore  Analysis,  Low,  John 
Wiley  &  Sons,  New  York,  1906. 


TITANIUM.  ioi 

originally  present  by  titrating  with  potassium  permanga- 
nate the  ferrous  salt  formed  (Newton,  Amer.  Jour.  Sci. 
xxv  (1908),  130). 

Separation.  The  general  method  for  the  separation 
of  titanium  from  the  other  members  of  the  aluminum 
group  is  to  boil  dilute  acidified  solutions  (vid.  Gravimetric 
Estimation).  The  titanium  precipitate,  however,  carries 
down  traces  of  other  elements,  as  aluminum  and  iron. 

From  iron  titanium  may  be  separated  (i)  by  passing 
hydrogen  sulphide  into  an  alkaline  solution  to  which  am- 
monium tartrate  has  been  added, — the  iron  sulphide  being 
precipitated  (Gooch,  Amer.  Chem.  Jour,  vn,  283) ;  (2)  by 
treating  a  mixture  of  ferrous  sulphide  and  titanic  acid 
with  sulphur  dioxide  (vid.  Extraction) ;  (3)  by  boiling  a 
neutral  solution  with  hydrogen  dioxide, — metatitanic  acid 
being  precipitated;  (4)  by  treating  a  solution  of  the  salts 
with  phenylhydrazine, — titanic  acid  being  precipitated 
(Allen,  Jour.  Amer.  Chem.  Soc.  xxv,  421). 

From  aluminum  titanium  may  be  separated  by  boiling 
a  solution  containing  them,  in  the  presence  of  an  alkali 
acetate  and  of  acetic  acid  to  about  seven  per  cent,  of  the 
whole  solution, — titanium  basic  acetate  being  precipitated 
(Gooch,  Amer.  Chem.  Jour,  vn,  283). 

From  cerium  and  thorium  titanium  may  be  separated  by 
precipitating  the  double  sulphates  of  those  elements  with 
potassium  sulphate.  Methods  for  the  separation  from 
zirconium  have  already  been  given  (vid.  Zirconium) .  From 
niobium  and  tantalum  titanium  may  be  separated  *  by 
repeated  fusions  with  acid  potassium  sulphate  and  extrac- 
tions of  the  melt  with  water, — the  titanium  being  in  soluble 
form.  A  satisfactory  separation  of  niobium  from  titanium 
may  be  effected  by  crystallizing  the  niobium-potassium 
oxyfluoride  from  35%  hydrofluoric  acid.  The  titanium 

*  E.  F.  Smith,  Proc.  Amer.  Philos.  Soc.  XLIV  (1905),  151,  177. 


102  THE  RARER  ELEMENTS. 

remains  in  solution  (C.  W.  Balke  and  E.  F.  Smith,  Jour. 
Amer.  Chem.  Soc.  xxx,  1637). 


EXPERIMENTAL  WORK  ON  TITANIUM. 

Experiment  i.  Extraction  of  titanium  salts  from  rutile. 
(a)  Mix  5  grm.  of  finely  powdered  mineral  with  about  30  grm. 
of  acid  potassium  sulphate  and  fuse  until  the  mass  is  free 
from  black  particles.  Pulverize  the  fused  mass  and  ex- 
tract with  cold  water,  stirring  frequently  until  solution 
is  complete.  Add  ammonium  sulphide,  filter  and  wash. 
Suspend  the  precipitate,  which  consists  mainly  of  titanium 
hydroxide  and  ferrous  sulphide,  in  water  and  pass  a  cur- 
rent of  sulphur  dioxide  through  the  liquid  until  the  ferrous 
sulphide  has  dissolved,  as  shown  by  the  disappearance 
of  the  dark  color.  Filter,  and  wash  the  titanium  hydroxide 
which  remains. 

(b)  Alternative  method.  After  having  dissolved  the  fused 
mass  in  cold  water  (vid.  (a))  add  about  20  grm.  of  tartaric  acid 
to  hold  up  the  titanium  hydroxide,  and  make  the  solution 
faintly  ammoniacal.  Pass  hydrogen  sulphide  through  until 
the  ferrous  sulphide  is  completely  thrown  down.  Filter,  add 
about  10  cm.3  of  concentrated  sulphuric  acid  to  the  filtrate, 
and  evaporate  in  a  porcelain  dish  tinder  a  draught  hood 
until  the  tartaric  acid  is  thoroughly  carbonized.  Allow 
the  mass  to  stand  until  cool,  add  water,  keeping  the  liquid 
cool  to  prevent  the  precipitation  of  the  titanium  hydroxide, 
and  decant  from  the  carbon  residue.  Filter  the  brown 
liquid  through  animal  charcoal  that  is  free  from  phos- 
phates and  precipitate  the  titanium  hydroxide  with  am- 
monium hydroxide  (R.  G.  Van  Name). 

Experiment  2.  Precipitation  of  titanium  hydroxide, 
(Ti(OH)4).  (a)  To  a  solution  containing  titanium  add 
sodium,  potassium,  or  ammonium  hydroxide.  Note  the 


EXPERIMENTAL   WVRK  ON   TITANIUM.  103 

comparative    insolubility  in    excess,  especially  in  ammo- 
nium hydroxide. 

(b)  Repeat  the  experiment,  using  the  alkali  carbonates. 
The  precipitate  is  the  same  as  in  (a). 

(c)  Note  the  solubility  of  the  freshly  precipitated  hy- 
droxide in  the  common  acids. 

(d)  Ignite  a  portion  of  the  precipitate  and  try  its  solu- 
bility in  acids. 

Experiment  3.  Precipitation  of  titanic  hydroxide  or 
acid  by  boiling.  (a)  Boil  a  dilute  acid  solution  of  titanic 
hydroxide.  Note  the  precipitation.  Filter,  and  test  the 
filtrate  with  ammonium  hydroxide. 

(b)  To  a  solution  of  titanic  acid  containing  enough 
free  acid  to  prevent  precipitation  on  boiling,  add  ammo- 
nium acetate.  Try  similarly  sodium  thiosulphate. 

Experiment  4.  Precipitation  of  basic  titanic  phosphate  > 
(Ti(OH)PO4).  To  a  solution  containing  titanic  acid  add  a 
little  sodium  phosphate  in  so1ution. 

Experimemt  5.  Color  tests  of  solutions  containing 
titanium,  (d)  To  an  acid  solution  containing  titanium 
add  hydrogen  dioxide.  Note  the  yellow  color  (TiO3  in 
solution) . 

(b)  To  a  solution  containing  titanium  add  a  piece  of 
metallic  zinc  and  enough  acid  to  start  the  action.      Note 
the  violet  color  which  develops. 

(c)  To  four  portions  of  dry  titanium  oxide  (TiO2)  or 
double  fluoride  (K2TiF6)  add  a  few  drops  of  strong  sul- 
phuric acid.     Bring  into  contact  with  the  first  a  few  parti- 
cles of  tannic  acid,  with  the  second  a  little  dry  pyrogallic 
acid,  with  the  third  some  morphia,  and  with  the  fourth  a 
little  salicylic  acid.     Note  the  red  color. 

Experiment  6.  Negative  test  of  titanium  compounds. 
Pass  hydrogen  sulphide  through  a  solution  containing 
titanium.  Note  the  absence  of  precipitation. 


104  THE  RARER  ELEMENTS. 


GERMANIUM,  Ge,  72.5. 

Discovery.  In  1886  Clemens  Winkler  announced  the 
presence  of  a  new  element  in  the  silver  mineral  argyrodite, 
which  had  been  discovered  the  previous  year  by  Weisbach, 
in  the  Himmelsfurst  mine  near  Freiberg  (Ber.  Dtsch. 
chem.  Ges.  xix,  210).  According  to  Winkler 's  analysis 
of  argyrodite,  the  sum  of  its  component  parts  was  seven  per 
cent,  less  than  it  should  have  been;  and  although  he  re- 
peated the  analysis  several  times  with  great  care,  the  out- 
come was  always  the  same.  This  uniformity  of  result  forced 
upon  him  the  conclusion  that  an  unknown  element  was 
probably  present ;  and  after  much  careful  and  patient  work 
he  was  successful  in  isolating  it  and  investigating  its  prop- 
erties. On  heating  the  mineral  out  of  contact  with  the  air, 
he  obtained  a  dark-brown  fusible  sublimate,  which  proved 
to  be  chiefly  two  sulphides,  that  of  the  new  element,  named 
by  him  Germanium,  and  the  sulphide  of  mercury. 

Occurrence.  Germanium  is  found  in  combination  in  a 
few  rare  minerals. 

Contains 
Ge 

Argyrodite,  4Ag2S-GeS2 6-7% 

Canfieldite,  4Ag2S  -  (Ge,Sn)S2 i .  82% 

in                 in 
Euxenite,  R(NbO3)3-R2(TiO3)3-|H2O traces 

Extraction.  Germanium  salts  have  been  extracted 
from  argyrodite  by  the  following  methods: 

(i)  A  Hessian  crucible  is  heated  to  redness,  and  small 
quantities  of  a  mixture  consisting  of  three  parts  of  sodium 
carbonate,  six  parts  of  potassium  nitrate,  and  five  parts  of 
the  mineral  are  gradually  put  in.  After  being  heated  for 
some  time  the  molten  mass  is  poured  into  an  iron  dish  and 
allowed  to  cool.  The  salt  mass  may  then  be  removed  from 


GERMJWUM.  105 

the  silver,  pulverized,  and  extracted  with  water.  The 
extract  is  treated  with  sulphuric  acid  and  evaporated 
until  all  the  nitric  acid  is  driven  off.  The  residue  is  dis- 
solved in  water  and  allowed  to  stand  until  the  oxide  of 
germanium  separates  from  the  solution. 

(2)  The  mineral  is  heated  to  redness  in  a  current  of 
hydrogen,  and  the  sublimate,  consisting  of  a  mixture  of 
germanium  and  mercuric  sulphides,  is  collected.  This 
sublimate  is  treated  with  ammonium  sulphide,  which  dis- 
solves the  sulphide  of  germanium,  forming  a  sulpho  salt. 
After  nitration,  the  solution  is  acidified  with  hydrochloric 
acid,  which  precipitates  the  germanium  as  the  sulphide. 

The  Element.  A.  Preparation.  Elementary  germanium 
may  be  obtained  (i)  by  heating  the  oxide  with  carbon; 
(2)  by  heating  the  oxide  in  a  current  of  hydrogen. 

B.  Properties.  Germanium  is  a  grayish- white,  metallic 
element,  having  a  fine  luster,  and  crystallizing  in  regular 
octahedra.  It  volatilizes  slightly  when  heated  in  hydrogen 
or  nitrogen  at  about  1350°  C.;  its  melting-point  is  about 
900°  C.  In  the  air  it  does  not  oxidize  at  ordinary  tem- 
peratures, but  when  heated  goes  over  to  the  oxide  GeO2. 
It  is  not  attacked  by  dilute  hydrochloric  acid,  is  oxidized 
by  nitric  acid,  and  is  dissolved  by  aqua  regia.  It  is  dis- 
solved also  by  sulphuric  acid,  with  the  evolution  of  sul- 
phur dioxide.  It  combines  directly  with  chlorine,  bromine, 
and  iodine.  Its  specific  gravity  is  5.46. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  germanium: 

Oxides GeO  GeO2 

Hydroxides Ge(OH)2  Ge(OH)4? 

Chlorides GeCl2  GeCl4 

Oxychloride GeOCl2 

Bromide GeBr4 

Iodide GeI4 


lo6  THE  RARER  ELEMENTS. 

Fluorides GeF2?  GeF4?;  K2GeF6;  H2GeF6 

Sulphides GeS  GeS2 

Chloroform GeHCl3 

Ethyl Ge(C2H5)4 

B.  Characteristics.  The  germanium  compounds  are 
known  in  two  conditions  of  oxidation;  those  of  the  higher 
form  are  the  more  stable  and  comprise  the  larger  group. 
Germanium  resembles  carbon  and  silicon  in  the  formation 
of  a  chloroform,  and  tin  in  the  formation  of  two  sulphides 
which  dissolve  in  ammonium  sulphide,  giving  sulpho  salts. 
The  sulphide  GeS2  is  a  white  powder  slightly  soluble  in 
water.  The  lower  sulphide,  GeS,  when  precipitated,  is  of  a 
reddish-brown  color;  when  obtained  by  the  reduction  of  the 
higher  sulphide  it  is  a  grayish-black  crys  alline  substance  of 
metallic  luster.  This  sulphide,  also,  is  slightly  soluble  in 
water.  The  dioxide  is  a  white  powder  soluble  in  alkalies,  but 
almost  completely  insoluble  in  acids.  The  tetrachloride  is 
a  liquid  which  fumes  in  damp  air  and  is  decomposed  by 
water. 

Estimation.  Germanium  is  usually  precipitated  as  the 
sulphide,  converted  by  nitric  acid  into  the  oxide  (GeO2), 
and  weighed  as  such. 

Separation.  Germanium  may  be  separated  from  most  of 
the  elements  by  the  formation  of  a  soluble  sulpho  salt  with 
ammonium  sulphide;  when  the  solution  is  acidified  the 
sulphide  is  precipitated.  Germanium  may  be  separated 
from  arsenic,  antimony,  and  tin  as  follows:  the  solution  of 
the  sulpho  salts  is  exactly  neutralized  with  sulphuric  acid, 
allowed  to  stand  twelve  hours,  and  filtered;  the  filtrate  is 
evaporated  to  a  small  volume,  treated  with  ammonia  and 
sulphate  of  ammonium,  acidified  with  sulphuric  acid,  and 
saturated  with  hydrogen  sulphide.  Germanium  sulphide 
is  precipitated  (Truchot,  Les  Terres  Rares,  294). 


CHAPTER  VII. 

« 

VANADIUM,  V,  51.2. 

Discovery.  As  early  as  1801  Del  Rio  announced  the 
discovery  of  a  new  metal  in  a  lead  ore  from  Zimapan, 
Mexico.  He  named  it  Erythronium  (epvflpos,  red},  be- 
cause its  salts  became  red  when  heated  with  acids 
(Annal.  der  Phys.  u.  Chem.  LXXI,  7).  Four  years  later 
Collet  Descotils  examined  the  supposed  metal  and  pro- 
nounced it  an  impure  oxide  of  chromium, — a  conclusion 
that  Del  Rio  himself  came  to  accept  (Ann.  de  Chim.  LIII, 
268). 

In  1830  Sef strom  found  an  unknown  metal  in  an  iron 
ore  from  Taberg,  Sweden.  He  proposed  for  it  the  name 
Vanadium,  from  Vanadis,  the  Scandinavian  goddess  more 
commonly  known  as  Freya  (Amer.  Jour.  Sci.  [i]  xx,  386). 
Almost  immediately  Wohler  showed  the  identity  of  vana- 
dium with  the  metal  described  by  Del  Rio  (Pogg.  Annal. 
xxi,  49)- 

Occurrence.  Vanadium  is  found  quite  widely  distributed, 
always  in  combination,  and  in  very  small  quantities : 

Contains 
V205. 

Vanadintie,  (PbCl)Pb4(VO4)3 8-21  % 

Descloizite,  (Pb,Zn)2(OH)VO4 20-22% 

Cuprodescloizite,  (Pb,Zn  Cu)2(OH)VO4 17-22% 

Calciovolborthite,  (Cu,Ca)2(OH)VO4 37~39% 

107 


io8  THE  RARER  ELEMENTS. 

Carnotite,  K20  -2U2O3-V2O5-3H20 19-20% 

Brackebuschite,  formula  doubtful 24-25% 

Psittacinite,  formula  doubtful 17-26% 

Volborthite,       "  "        14-15% 

Pucherite,  BiVO4 22-27% 

Roscoelite,  silicate,  formula  doubtful 21-29% 

Ardennite,        "  "  "       '. traces  -  9% 

Mottramite,  (Cu,Pb)6V2Oio-2H2O 17-18% 

Patronite,*  VS4? i8-iQ%V 

Rizopatronite,  vid.  Patronite. 

Vanadium  has  been  detected  also  in  some  copper,  lead, 
and  iron  ores,  in  certain  clays  and  basalts,  in  soda  ash  and 
phosphate  of  soda,  and  in  some  hard  coals. 

Extraction.     Vanadium    salts  may    be   extracted   from 
mineral  sources  by  the  following  methods. 

(1)  The  mineral  is  fused  with  potassium  nitrate,  and 
the  potassium  vanadate  thus  formed  is  extracted  with  water. 
By  the  addition  of  a  soluble  lead  or  barium  salt  to  the 
solution  the  lead  or  barium  vanadate  is  precipitated.     This 
insoluble  vanadate  is  decomposed  by  means  of  sulphuric 
acid,  and  the  barium  or  lead  sulphate  is  filtered  off.     By 
saturation    of  the   filtrate   with   ammonium   chloride   the 
ammonium  vanadate  is  precipitated. 

(2)  Finely  ground  carnotite  is  decomposed  by  nitric  acid, 
and  the  solution  is  treated  with  sodium  hydroxide  and 
sodium  carbonate;  the  vanadium  is  left  in  soluble  form  as 
sodium  vanadate.     If  vanadinite  is  used  instead  of  carnotite 
the  lead  must  be  precipitated  from  the  nitric  acid  solution 
by  hydrogen  sulphide,  and  the  excess  of  hydrogen  sulphide 
removed  from  the  filtrate  by  boiling,  before  the  treatment 
with  sodium  hydroxide. 

*  Hillebrand,  Jour.  Amer.  Chem.  Soc.  xxix,  1019. 


VANADIUM.  109 

(3)  The  mineral,    e.   g.,   carnotite,   is   fused  with  acid 
potassium  sulphate,  the  melt  extracted  with  water,  and  the 
solution  evaporated,  when  the  double  sulphates  of  vanadium 
and  uranium  with  potassium  crystallize  out.     The  vanadium 
is  reduced  by  zinc,   and  precipitated  by  ammonium  hy- 
droxide and  ammonium  carbonate. 

(4)  A    patented    process   by  J.    H.    Haynes    (Mineral 
Resources  U.  S.,  1906,  page  531)  for  treatment  of  carnotite 
is  of  interest.     The  powdered  mineral,  previously  roasted, 
is  agitated  with  boiling  sodium  carbonate,  which  extracts 
vanadium  and  uranium.     From  this  solution  the  uranium 
is  precipitated  by  sodium  hydroxide. 

The  Element.  A.  Preparation.  Elementary  vanadium 
may  be  prepared  (i)  by  long  heating  of  the  dichloride  in  a 
current  of  hydrogen;  (2)  by  the  electrolysis  of  the  fluoride 
(VF3)  (Gin,  Chem.  News,  LXXXVIII,  38) ;  (3)  by  the  action 
of  "mischmetal"  (metals  of  Ce  and  Y  groups)  on  the  oxide 
(V2O5)  (Muthmann  and  Weiss,  Liebig  Ann.,  cccxxxvn,  370; 
CCCLV,  58). 

B.  Properties.  Vanadium  is  a  non-magnetic,  light- 
gray  powder,  somewhat  crystalline  in  appearance.  It 
oxidizes  slowly  in  the  air  at  ordinary  temperatures,  but 
more  rapidly  when  heated,  going  through  various  degrees 
of  oxidation  and  showing  a  characteristic  color  for  each 
oxide— brown  (V2O),  gray  (V2O2),  black  (V2O3),  blue  (V2O4), 
and  red  (V2O5).  Upon  the  application  of  heat  vanadium 
unites  with  chlorine,  forming  the  chloride  VC14;  at  a  red 
heat  it  combines  with  nitrogen,  giving  the  nitride  VN.  It 
is  insoluble  in  hydrochloric  and  dilute  sulphuric  acids, 
and  soluble  in  nitric,  hydrofluoric,  and  concentrated  sul- 
phuric acids.  It  is  not  attacked  by  alkaline  solutions,  but 
with  melted  alkalies  forms  the  alkali  vanadates,  with  the 
evolution  of  hydrogen.  The  specific  gravity  of  vanadium 
is  5.5.  The  melting-point  of  the  metal  is  1680°  C. 


HO  THE  RARER  ELEMENTS 

Compounds.*     A.   Typical  forms.     The   following   may 
be  considered  typical  compounds  of  vanadium: 


Oxides V20  V2O2      V2O3              VA                      V2O6 

Chlorides VC12       VC13               VC14 

Oxychlorides ....  VOC1             VOC12 

Bromide VBr3 

Oxybromides VOBr,                   VOBr, 

Fluorides VF3+  6H2O                              VF5 

Double  fluorides. .  VF3  with  KF,  CoF8,  NiF2,  etc. 

Sulphides V^,       V2S3                                              V,S3O2 

V2S5 

Sulpho  salts Na3VS3O 

(NH4)3VS4,etc. 

Sulphate VSO4        V2(SO4)K2SO4+24H2O           VACSOJ, 

Nitrides VN                                             VN2 

Vanadates,  ortho,  R3VO4 
pyro, 


meta,  RVO3 


complex,  VA  ^th  P2O5,  MoO3,  WO3,  SiO2,  AsO5,  etc. 
B.  Characteristics.  The  vanadium  compounds  are 
known  in  five  conditions  of  oxidation,  represented  by  the 
five  oxides.  Of  these  conditions  the  highest  is  the  most 
stable  and  is  known  in  the  largest  number  of  salts,  the 
vanadates.  Vanadic  •  pentoxide  is  reddish  yellow  in  color, 
and,  like  phosphoric  pentoxide,  it  dissolves  readily  in  the 
alkali  hydroxides  and  carbonates.  The  alkali  vanadates 


thus  formed  are  of  the  ortho,  pyro,  and  meta  types, 

RV2O7;  RVO3).  The  vanadates  are  generally  pale  yellow 
in  color.  They  are  soluble  in  the  stronger  acids  and  with 
the  exception  of  the  alkali  vanadates  insoluble  in  water. 
Vanadic  acid  is  easily  reduced  by  reducing  agents  to  the 
tetroxide  condition,  when  the  solution  becomes  blue.  More 
powerful  reducing  agents  carry  the  reduction  further,  to 

*  See  also  Das  Vanadin  und  seine  Verbindungen,  Ephraim,  pub.  by  Ferdi- 
nand Enke,  Stuttgart,  1904;  Rutter,  Zeitsch.  anoig.  Chem.  Ln.  368;  Prandtl, 
Ber.  Dtsch.  chem.  Ges.  XL,  2125;  Koppei,  Zeitsch.  EJectrochem.  x,  141. 


VANADIUM.  Ill 

the  trioxide,  or  even  the  dioxide  condition,  but  only  long- 
continued  heating  in  a  current  of  hydrogen  brings  about 
the  reduction  to  the  monoxide  and  the  element. 

Hydrogen  sulphide,  acting  upon  vanadic  acid,  reduces 
it  to  the  tetroxide  condition  or  even  below,  with  a  sepa- 
ration of  sulphur.  Ammonium  sulphide  gives  the  dark- 
brown  solution  of  a  sulpho  salt,  ((NH4)3S3VO?),  and  this 
solution,  when  acidified,  gives  a  brown  oxysulphide  (V2S3O2). 
Vanadium  resembles  arsenic,  phosphorus,  and  nitrogen, 
both  in  the  chemical  structure  of  its  compounds  and  in 
their  behavior  toward  reagents. 

Estimation.*  A.  Gravimetric.  Vanadium  is  usually 
weighed  as  the  pentoxide,  (V2O5),  obtained  (i)  by  precipi- 
tation of  lead  or  barium  vanadate,  treatment  with  sulphuric 
acid,  filtration,  evaporation  of  the  filtrate,  and  ignition;  (2) 
by  precipitation  of  mercury  vanadate  and  ignition,  the 
pentoxide  being  left ;  or  (3)  by  precipitation  of  the  ammo- 
nium salt  by  ammonium  chloride  and  ignition  (Berzelius, 
Pogg.  Annal.  xxn,  54;  Gibbs,  Amer.  Chem.  Jour,  v,  371; 
Gooch  and  Gilbert,  Amer.  Jour.  Sci.  [4]  xiv,  205). 

B.  Volumetric.  Vanadium  may  be  estimated  volu- 
metrically  (i)  by  reduction  from  the  condition  of  the  pent- 
oxide  to  that  of  the  tetroxide  by  sulphur  dioxide,  hydro- 
gen sulphide,  or  zinc  and  free  acid,  and  reoxidation  by 
permanganate  (Hillebrand,  Jour.  Amer.  Chem.  Soc.  xx, 
461;  Gooch  and  Gilbert,  Amer.  Jour.  Sci.  [4]  xv,  389); 
(2)  by  effecting  the  reduction  by  boiling  with  hydrochloric 
acid  or  with  potassium  bromide  or  iodide  in  acid  solution, 
according  to  the  typical  equation  V2O5+  2HC1=V2O4+ 
H2O+C12.  The  chlorine,  bromine,  or  iodine  may  be  dis- 

*  See  Die  analytische  Chemie  des  Vanadins,  V.  von  Klecki,  pub.  by  Leopold 
Voss,  Hamburg,  1894;  Campagne,  Ber.  Dtsch.  chem.  Ges.  xxxvi,  3164;  Beard, 
Ann.  Chim.  anal,  et  appl.  x,  41;  Chem.  Zentr.  1905  [i],  960.  For  estimation 
in  ores,  see  also  Low's  Technical  Methods  of  Ore  Analysis;  Blair,  Jour.  Amer. 
Chem.  Soc.  xxx,  1229;  Campbell,  ibid,  xxx,  1233. 


112  THE  R4RER    ELEMENTS. 

tilled  and  determined  by  suitable  means  in  the  distillate 
(Holverscheit,  Dissertation,  Berlin,  1890;  Friedheim,  Ber. 
Dtsch.  chem.  Ges.  xxvin,  2067;  Gibbs,  Proc.  Amer.  Acad. 
x,  250;  Gooch  and  Stookey,  Amer.  Jour.  Sci.  [4]  xiv,  369; 
Gooch  and  Curtis,  Amer.  Jour.  Sci.  [4]  xvn,  4),  or  the 
residue  after  boiling  may  be  rendered  alkaline  by  potas- 
sium bicarbonate,  and  reoxidation  effected  by  standard, 
iodine  solution  (Browning,  Amer.  Jour.  Sci.  [4]  n,  185); 
(3)  or  the  reduction  may  be  accomplished  by  boiling  with 
tartaric,  oxalic,  or  citric  acid,  and  reoxidation  effected  as 
outlined  above  (Browning,  Zeitsch.  anorg.  Chem.  vn,  158, 
and  Amer.  Jour.  Sci.  [4]  n,  355).  (4)  Vanadium  and  molyb- 
denum may  be  estimated  when  together  by  heating  their 
acids  in  the  presence  of  sulphuric  acid  and  treating  with 
sulphur  dioxide,  which  reduces  the  vanadium  to  the  con- 
dition of  the  tetroxide,  without  affecting  the  molybdic  acid. 
The  vanadium  may  be  estimated  as  in  (i)  by  permanganate. 
The  oxidized  solution  may  then  be  passed  through  a  Jones 
reductor  into  a  receiver  charged  with  a  ferric  salt.  This 
process  reduces  the  molybdenum  to  the  sesquioxide  (Mo2C>3) 
condition  and  the  vanadium  to  the  dioxide  (V202)  condition, 
and  registers  the  reduction  in  the  ferric  salt.  The  reoxida- 
tion is  again  effected  with  permanganate  and  the  amount  of 
vanadium  being  known  from  the  first  titration  the  molyb- 
denum may  be  calculated  from  the  second  (Edgar,  Amer. 
Jour.  Sci.  xxv  (1908),  332).  (5)  By  a  similar  process  of 
differential  reduction  and  oxidation  Edgar  (Amer.  Jour. 
Sci.  xxvi  (1908),  79)  estimates  iron  and  vanadium  in  the 
presence  of  each  other.  After  the  solution  containing 
vanadic  acid  and  iron  has  been  reduced  by  sulphur  dioxide 
the  oxidation  by  permanganate  proceeds  according  to  the 
equation : 


VANADIUM.  113 

After   the   reduction   by   zinc  in   the  Jones  redactor  the 
oxidation  is  as  follows  : 


From  these  equations,  the  amount  of  permanganate  used 
being  known,  the  amount  of  iron  and  vanadium  present 
may  be  calculated. 

Separation.  Vanadium  may  be  separated  from  the 
majority  of  the  metallic  bases  (i)  by  fusion  of  material 
containing  it  with  sodium  carbonate  and  potassium  nitrate 
and  extraction  with  water,  vanadium  dissolving  as  sodium 
vanadate;  or  (2)  by  treatment  of  a  solution  containing 
a  vanadate  with  ammonium  sulphide  in  excess,  vanadium 
remaining  in  solution  as  a  sulpho  salt. 

From  arsenic  vanadium  may  be  separated  (i)  by  treat- 
ment with  hydrogen  sulphide,  after  reduction  by  means 
of  sulphur  dioxide,  the  arsenic  being  precipitated  as  the 
sulphide  As2S3;  (2)  by  heating  the  sulphides  of  vanadium 
and  arsenic  in  a  current  of  hydrochloric  -acid  gas  at  i5o°C., 
the  arsenic  forming  a  volatile  compound  (Field  and  Smith, 
Jour.  Amer.  Chem.  Soc.  xvm,  1051). 

From  phosphorus  vanadium  may  be  separated  by  re- 
duction of  vanadic  acid  by  means  of  sulphur  dioxide,  and 
precipitation  of  the  phosphorus  as  phosphomolybdate. 

From  molybdenum  the  separation  may  be  accomplished 
by  the  action  of  hydrogen  sulphide  upon  a  solution  of  vana- 
dic and  molybdic  acids  under  pressure,  —  molybdenum  sul- 
phide being  precipitated,  —  or  by  the  action  of  ammonium 
chloride  in  excess  upon  a  solution  containing  an  alkali 
vanadate  and  molybdate,  —  ammonium  me  ta  vanadate  being 
precipitated  (Gibbs,  Amer.  Chem.  Jour,  v,  371). 

From  tungsten  vanadium  may  be  separated  by  the 
ammonium  chloride  method  (vid.  Separation  from  molyb- 
denum, above)  (Gibbs,  Amer.  Chem.  Jour,  v,  379). 


H4  THE  RARER  ELEMENTS. 

EXPERIMENTAL  WORK  ON  VANADIUM. 

Experiment  i.  Extraction  of  vanadium  from  carnotite. 
Treat  20  gnu.  of  the  finely  powdered  mineral  with  hydro- 
chloric acid,  heat  until  nothing  further  dissolves,  add  an 
equal  volume  of  water,  and  filter.  Evaporate  the  filtrate 
nearly  to  dryness,  add  enough  nitric  acid  to  oxidize  the 
vanadium  to  vanadic  acid.  To  the  oxidized  solution  add 
sodium  hydroxide  in  excess,  and  filter.  The  filtrate  should 
contain  sodium  vanadate  together  with  an  excess  of  sodium 
hydroxide.  Neutralize  carefully  with  acetic  acid,  and  test 
for  vanadium  by  any  of  the  following  experiments : 

Experiment  2.     Formation  of  insoluble  vanadates  of  lead, 

ii  ii 

silver,  and  barium,    (R3(VO4)2,   ortho;  or  R(VO3)2,  metd). 

(a)  To  a  solution  of  an  alkali  vanadate  (ortho  or  meta) 
add  a  solution  of  lead  acetate. 

(b)  Repeat  the  experiment,  substituting  silver  nitrate 
for  lead  acetate.     Note  the  flocky  character  of  the  pre- 
cipitate when  shaken. 

(c)  Use  barium  chloride  as  the  precipitant. 

(d)  Try  the  action  of  nitric  and  acetic  acids  upon  these 
salts. 

Experiment  3.  Formation  of  vanadium  pentoxide,  (V2O5) , 
from  ammonium  vanadate.  Evaporate  a  solution  of  am- 
monium vanadate  to  dryness  and  ignite.  Note  the  crystals 
of  the  pentoxide. 

Experiment  4.  Precipitation  of  vanadium  oxy sulphide, 
(V2S3O2).  (a)  To  a  solution  of  an  alkali  vanadate  add 
ammonium  sulphide.  Note  the  darkening  in  color 
((NH4)3S3VO?).  Acidify  the  solution  with  hydrochloric 
acid.  Note  the  precipitation  of  the  oxysulphide. 

(b)  Note  that  hydrogen  sulphide  in  an  acid  solution 
precipitates  sulphur  and  leaves  a  blue  solution  (V2O4). 

Experiment    5.       Reduction    of    vanadic    acid,    (V2O5). 


NIOBIUM  (COLUMBIUM);   TAUT  ALUM.  115 

(a)  To  a  solution  of  an  alkali  vanadate  add  a  crystal  of 
tartaric  acid  and  boil.  Note  the  yellow-red  color  of  the 
vanadic  acid  when  the  tartaric  acid  is  first  added,  and 
the  change  to  blue  (V2O4)  produced  on  boiling. 

(6)  Neutralize  the  blue  solution  obtained  in  (a)  with 
sodium  or  potassium  bicarbonate,  and  add  a  solution  of 
iodine  in  potassium  iodide  until,  after  the  liquid  has  stood 
for  a  few  moments,  the  color  of  the  iodine  remains.  Bleach 
the  excess  of  iodine  with  an  alkaline  solution  of  arsenious 
oxide.  Note  that  the  blue  color  has  disappeared  and  the 
vanadium  is  in  the  condition  of  the  pentoxide  (V2O5). 

(c)  Try  the  action  of  other  reducing  agents  upon  vanadic 
acid,  e.g.  oxalic  acid,  hydrochloric  acid,  stannous  chloride, 
zinc  and  hydrochloric  acid,  etc.  Note  that  the  zinc  and 
hydrochloric  acid  carry  the  reduction  below  the  tetroxide 
condition  ( V2O4) . 

Experiment  6.  Delicate  tests  for  vanadium,  (a)  Acidify 
a  solution  of  an  alkali  vanadate  and  add  hydrogen  dioxide. 
Note  the  red  color  (Maillard). 

(b)  Bring  a  few  drops  of  the  vanadium  solution  into 
contact  with  a  drop  of  strong  sulphuric  acid  to  which  a 
crystal  of  strychnine  sulphate  has  been  added.  Note 
the  color,  changing  from  violet  to  rose. 

Experiment  7.  Borax-bead  tests  for  vanadium.  Fuse  a 
little  ammonium  vanadate  into  a  borax  bead  and  test  the 
action  of  the  reducing  and  oxidizing  flames  upon  it. 

NIOBIUM  (COLUMBIUM),  Nb(Cb),  93 . 5 ;  TANTALUM,  Ta,  181. 

Discovery.  Hatchett,  while  working  with  some  chro- 
mium minerals  in  the  British  Museum  in  1 80 1 ,  came  across 
a  black  mineral  very  similar  to  those  upon  which  he  was 
engaged  (Phil.  Trans.  Roy.  Soc.  (1802),  49).  He  obtained 
permission  to  examine  it  and  found  it  to  consist  almost 
wholly  of  iron  and  an  earth  which  did  not  conform  to 


u6  THE  RARER   ELEMENTS. 

any  known  test.  He  described  it  as  "a  white,  tasteless 
earth,  insoluble  in  hot  and  cold  water,  acid  to  litmus, 
infusible  before  the  blowpipe,  and  not  dissolved  by  borax. ' ' 
The  only  acid  which  dissolved  it  was  sulphuric.  Since 
the  mineral  was  of  American  origin,  coming  from  Con- 
necticut, the  discoverer  named  it  Columbite,  and  the 
element  Columbium. 

About  a  year  later  Ekeberg  (Crell  Annal.  (1803)  i,  3), 
while  investigating  a  mineral  from  Kimito,  Finland,  which 
closely  resembled  columbite,  discovered  a  "metal"  which 
resembled  tin,  tungsten,  and  titanium.  It  proved  to  be 
none  of  these,  but  in  fact  a  new  element.  He  named  it 
Tantalum,  "because  even  when  in  the  midst  of  acid  it 
was  unable  to  take  the  liquid  to  itself. ' '  Indeed,  insolu- 
bility in  acid  seemed  to  be  the  chief  characteristic  of  the 
new  substance. 

The  apparent  similarity  of  columbium  and  tantalum 
suggested  that  they  might  be  identical,  and  in  order  to 
settle  this  question  Wollaston  (Phil.  Trans.  Roy.  Soc. 
xcix,  246)  in  1809  began  to  work  on  tantalite  and  a  speci- 
men of  the  same  columbite  that  Hatchett  had  examined. 
He  found  that  the  freshly  precipitated  acids  were  both 
soluble  in  concentrated  mineral  acids;  if  they  were  dried 
it  was  necessary  to  fuse  them  both  with  caustic  alkalies 
before  they  could  be  dissolved.  Both  were  held  up  if 
ammonium  hydroxide  was  added  in  the  presence  of  citric, 
tartaric,  or  oxalic  acid.  Having  found  practically  the  same 
reactions  with  both  acids,  he  concluded  that  the  elementary 
substances  were  the  same.  The  specific  gravity  of  tantalite, 
however,  was  7.95,  and  that  of  columbite  5.91.  This  he 
explained  by  suggesting  different  conditions  of  oxidation 
or  different  States  of  molecular  structure.  These  con- 
clusions were  accepted,  and  for  many  years  the  element 
was  called  indifferently  tantalum  and  columbium. 

In  1844  Rose  began  to  investigate  the  same  subject. 


NIOBIUM   (COLUMBIUM);   TANTALUM.  117 

His  work  on  the  columbites  of  Bodenmais  and  Finland 
led  him  to  the  belief  that  there  were  two  distinct  acids 
in  the  columbite  from  Bodenmais,  one  similar  to  that  in 
tantalite,  the  other  containing  a  new  element,  to  which 
he  gave  the  name  Niobium,  from  Niobe,  daughter  of  Tan- 
talus. Though  niobium  proved  to  be  Hatchett's  colum- 
bium,  Rose's  name  for  the  element  has  been  the  one  more 
generally  adopted. 

Occurrence.*  Niobium  and  tantalum  are  found,  each 
in  combination,  in  various  rare  minerals.  They  usually, 
though  not  invariably,  occur  together. 

Contains 
Nb205  Ta205 

Pyrochlore,  RNb2O6-R(Ti,Th)O3 47~58% 

Marignacite,  vid.  Pyrochlore 55~56%     5-  6% 

Koppite,  R2Nb207-fNaF 61-62% 

Hatchettolite, 

2R(Nb,Ta)2O6-R2(Nb,Ta)2O7 63-67% f 

Microlite,  Ca2Ta2O7 7-  8%  68-69% 

Fergusonite,  (Y,Er,Ce)(Nb,Ta)O4 14-46%     4~43% 

in 
Sipylite,  RNbO4 47~48%     i-  2% 

Columbite,  (Fe,Mn)(Nb,Ta)2O6 26-77%  i~77% 

Tantalite,  FeTa2O6 3~4Q%  42-84% 

Skogbolite,      "       3~4Q%  42-84% 

Tapiolite,  Fe(Nb,Ta)2O6 11-12%  73~74% 

Mossite,  Fe(Nb,Ta)206 83 %f 

ii  in 

Yttrotantalite,  RR2(Ta,Nb)4O15 12-13%  46-47% 

in  ii 
Samarskite,  R2R3(Nb,Ta)6O21 41-56%  14-27% 

Stibiotantalite,  Sb2O3(Ta,Nb)2O5? 7  -  5   %         5 1  % 

Annerodite,  complex 48-49% 

*  See  also  Schilling,  Zeitsch.  angew.  Chem.  (1905),  883. 
tNb2O5+Ta2O5. 


Ii8  THE  RARER  ELEMENTS 

Contains 
Nb2O6 

Hielmite,  complex 4-16%  55-72% 

in  in 

^schynite,  R2Nb4O13.R2(Ti,Th)5O13 32-33%  21-22% 

Polymignite, 

5RTiO3-5RZrO3-R(Nb,Ta)2O6 11-12%     1-2% 

in  in 

Euxenite,  R(NbO3)3-R2(TiO3)3-|H20 18-35% 

in  in 

Polycrase,  R(NbO3)3 - 2R2(TiO3)3 . 3H2O .  .  .    19-25 %     o-  4% 

Wohlerite,  i2R(Si,Zr)O3-RNb2O6 12-14% 

Lavenite,  R(Si,Zr)O3-Zr(SiO3)2-RTa2O6.  .  o-  5%* 

Dysanalyte,  6RTiO3  •  RNb2O6 0-23%     0-5% 

Kochelite,  vid.  Fergusonite 29-30% 

Arrhenite,  complex 2-3%  21-22% 

Blomstrandite,  complex 49-50%* 

Rogersite, 18-20% 

Adelpholite,  vid.  Sipylite 41-42%* 

Vietingshofite,  vid.  Samarskite 51  %* 

Eucolite,  complex  silicates 2-  4%* 

Melanocerite,  complex  silicates 3-  4% 

Caryocerite,  vid: Melanocerite 3-i% 

Steenstrupine,  vid.  Melanocerite 0-1.5%* 

Cyrtolite,  silicate 0-1.5%* 

Naegite,  silicate 4%          7% 

Tritomite,  complex  silicates 1-3% 

Cassiterite  (Ainalite),  SnO2 0-9% 

Extraction.  Salts  of  niobium  and  tantalum  may  be 
extracted  from  columbite  or  tantalite  by  either  of  the  fol- 
lowing methods : 

(i)  The  mineral  is  fused  with  six  parts  of  potassium 
bisulphate,  the  fused  mass  is  pulverized  and  treated  with 
hot  water  and  dilute  hydrochloric  acid.  The  residue  is 

*Nb,08+Ta205. 


(    UNIVERSITY 

OF 


N1OB1UM  (COLUMBIUM};   TANTALUM.  119 

then  digested  with  ammonium  sulphide  to  remove  tin,  tung- 
sten, etc.,  and  again  warmed  with  dilute  hydrochloric  acid. 
After  this  treatment  it  is  washed  thoroughly  with  water 
and  dissolved  in  hydrofluoric  acid.  Filtration  is  followed 
by  the  addition  of  potassium  carbonate  to  the  clear  solu- 
tion until  a  precipitate  begins  to  form.  The  potassium 
and  tantalum  double  fluoride  separates  first  in  needle- 
like  crystals,  after  which  the  niobium  oxyfluoride  crys- 
tallizes in  plates. 

(2)  The  mineral  is  fused  with  three  parts  of  acid  potas- 
sium fluoride  (vid.  Experiment  i). 

The  Elements.  I.  NIOBIUM.  A.  Preparation.  The  ele- 
ment niobium  may  be  obtained  (i)  by  reducing  the  oxide 
with  aluminum  (Goldschmidt  reaction)  ;  (2)  by  mixing  the 
pentoxide  with  paraffin,  drawing  into  fibers,  and  reducing 
to  the  tetroxide  by  heating  with  carbon.  The  tetroxide, 
being  a  conductor,  is  reduced  to  the  metal  by  heating 
highly  in  vacua  (von  Bolton,  Zeitsch.  Electrochem.  xm, 
I45)'»  (3)  by  heating  the  oxide  with  "  mischmetal" 
(Muthmann  and  Weiss,  Liebig  Ann.  cccxxxvn,  370;  CCCLV, 

58). 

B.  Properties.  Niobium  is  a  metallic  element  of  steel- 
gray  color  and  brilliant  luster.  Heated  in  the  air  it  is 
only  slowly  oxidized  to  Nb2O4.  It  is  practically  unattacked 
by  acids,  but  is  attacked  by  fused  alkalies  and  at  red  heat 
by  chlorine.  It  combines  with  hydrogen  and  nitrogen.  It 
is  as  hard  as  wrought  iron,  and  is  malleable  and  ductile. 
Its  fusing-point  is  1950°  C.,  and  its  specific  gravity  is 
,  about  7. 

II.  TANTALUM.*  A.  Preparation.  Elementary  tanta- 
lum may  be  obtained  (i)  by  heating  the  potassium  and 
tantalum  fluoride  (IQTaFy)  with  potassium  and  extract- 


*  Von  Bolton,  Zeitsch.  angew.  Chem.  (1906),  1537;     Muthmann,  Liebig  Ann, 
CCCLV,  58. 


120  THE  R4RER  ELEMENTS. 

ing  the  potassium  fluoride  with  water;  (2)  by  heating  the 
oxide  with  "  mischmetal." 

B.  Properties.  Tantalum  in  the  elementary  condition 
is  a  little  darker  in  color  than  platinum,  and  is  about  as 
hard  as  soft  steel.  It  can  be  hammered  into  plates  and 
drawn  into  wire.  In  the  cold  it  is  very  inert.  Heated 
to  400°  C.  it  becomes  yellow,  and  to  600°  bluish.  At  low 
redness  it  burns  to  the  oxide.  Its  melting-point  is  given 
as  2300°  C.  (Bolton)  and  2900°  C.  (Waidner).*  It  com- 
bines at  low  redness  with  hydrogen,  nitrogen,  and  chlorine. 
It  combines  readily  with  carbon,  forming  several  carbides. 
The  metal  is  not  attacked  by  hydrochloric,  nitric,  or 
sulphuric  acid,  nor  by  alkaline  solutions,  but  is  attacked 
by  hydrofluoric  acid.  The  specific  gravity  of  melted  and 
drawn  tantalum  is  16.8;  that  of  the  metal  in  powder  form 
(hydrogen  and  oxygen  being  present),  14. 

Compounds,  f  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  niobium  and  tantalum : 

Oxides Nb2O2 

Nb2O4  Ta2O4 

Nb205  Ta206 

Chlorides TaCl2+ 2H20 

NbCl3 

NbCl5  Tad. 

Oxychloride NbOCl3 

Bromides NbBr5  TaBr5 

Oxybromide.  .  . .     NbOBr, 

Fluorides NbF5  TaF5 

Oxyfluoride NbOF3 


3 


*  Waidner  and  Burgess,  J.  physique  vi,  380;  Chem.  Abs.,  Amer.  Chem.  Soc. 
H,  739  (Mar.  '08). 

t  See  also  E.  F.  Smith  and  others,  Jour.  Amer.  Chem.  Sex;.  XXVU,  1140,  1216, 
1369;  xxx,  1637;  Chabrie,  Compt.  rend.  CXLIV,  804. 


NIOBIUM  (COLUMBIUM);   TANTALUM.  12 1 

Fluotantalates  . .  K2TaF7 

Na2TaF7 
(NH4)2TaF7 

Double  fluorides .     *KF  .;yNbOF3 )  rtvt)ican 
^KF.yNb02F{  Atypical) 

Sulphide Ta2S4 

Silicide TaSi2 

Nitride Ta3N, 

Niobates K8Nb6O19  + 1 6H2O 

K6Nb4013 

2K2Nb4O 

K4Nb2O7 

Na16Nb14043 

Na2Nb2O6,  etc. 

Tantalates Of  types  R8Ta6O19  and  RTaO3, 

with  Na,  K,  NH4,  Ba,  and  Mg. 

B.  Characteristics.  The  compounds  of  niobium  closely 
resemble  those  of  tantalum,  both  in  chemical  form  and  in 
behavior  toward  reagents.  The  two  elements  are  closely 
associated  in  minerals  (vid.  Occurrence) .  The  lower  oxides 
of  niobium  are  dark  powders  which  oxidize  when  heated. 
The  dioxide  is  soluble  in  hydrochloric  acid,  while  the  tetrox- 
ide  is  not  attacked  by  acids.  The  pentoxide  is  a  yellowish- 
white  amorphous  powder  somewhat  soluble  in  concen- 
trated sulphuric  acid  before  ignition,  but  insoluble  after. 
Niobium  pentachloride  is  a  yellow  crystalline  substance 
prepared  by  passing  sulphur  chloride  (82012)  in  the  form  of 
vapor  over  the  pentoxide.  It  tends  to  form  the  oxy- 
chloride  in  the  presence  of  water.  It  is  reduced  to  the 
trichloride  when  its  vapor  is  passed  through  a  red-hot  tube. 
The  fluoride  is  formed  by  the  action  of  hydrofluoric  acid 
upon  the  pentoxide 

Tantalum  tetroxide  is  a  very  hard,  dark-gray,  porous 
mass  which  is  not  attacked  by  acids.  When  heated  it 


122  THE  R/tRER  ELEMENTS 

goes  over  to  the  higher  oxide.  The  pentoxide  of  tanta- 
lum is  a  white  powder  which  is  somewhat  soluble  in  acids. 
The  chloride  and  fluoride  of  tantalum  are  formed  similarly 
to  the  corresponding  salts  of  niobium  and  resemble  them 
in  general  behavior.  Niobates  and  tantalates  are  obtained 
by  fusing  the  oxides  with  caustic  alkalies;  these  salts  are 
soluble.  The  tantalum  compounds  give  no  color  test  with 
morphia,  tannic  acid,  or  pyrogallic  acid. 

Estimation.  A.  Gravimetric.  Niobium  and  tantalum 
are  ordinarily  weighed  as  the  oxides  Nb2O5  and  Ta2O5, 
obtained  from  ignition  of  the  acids. 

B.  Volumetric.  Niobium  may  be  estimated  volumet- 
rically  by  reduction  from  the  condition  of  the  pentoxide  to 
that  of  the  trioxide  by  means  of  zinc  and  hydrochloric 
acid  in  a  current  of  carbon  dioxide,  and  oxidation  with 
permanganate  (Osborn,  Amer.  Jour.  Sci.  [3]  xxx,  329). 

Separation.  The  method  usually  employed  for  the 
separation  of  niobium  and  tantalum  from  the  elements 
with  which  they  are  generally  associated — namely,  tita- 
nium, zirconium,  and  thorium — is  that  of  fusion  with  acid 
potassium  sulphate  (vid.  Titanium).  From  tin  and  tung- 
sten they  may  be  separated  by  repeated  fusions  of  the 
oxides  with  sodium  carbonate  and  sulphur  (E.  F.  Smith, 
Proc.  Amer,  Philos.  Soc.  XLIV,  157). 

The  separation  of  niobium  from  tantalum  is  one  of 
the  most  difficult  of  analytical  problems.  Marignac's 
method  (Ann.  Chim.  Phys.  [4]  vui,  i),  based  upon  the 
difference  in  solubility*  between  the  tantalum-potassium 
fluoride  (K2TaF7)  and  the  niobium-potassium  oxyfluoride 
(2KF-NbOF3-f  H2O),  is  the  most  satisfactory  known. 

*  K2TaF7  is  soluble  in  151-157  parts  of  cold  water.     2KF-NbOF3+H,O  is 
soluble  in  12-13  Parts  of  cold  water. 


EXPERIMENTAL  WORK  ON  NIOBIUM  AND  TANTALUM.       123 


EXPERIMENTAL    WORK    ON    NIOBIUM    AND 
TANTALUM. 

Experiment  i.  Extraction  of  niobium  and  tantalum 
salts  from  columbite  or  tantalite.  Mix  5  grm.  of  the  finely 
ground  mineral  with  15  grm.  of  acid  potassium  fluoride 
and  fuse  thoroughly.  Pulverize  the  fused  mass  and  extract 
with  boiling  water  containing  a  little  hydrofluoric  acid. 
Evaporate  to  about  200  cm.3  and  allow  the  liquid  to  stand. 
The  potassium  and  tantalum  fluoride  separates  first  in 
needle-like  form;  the  niobium  and  potassium  oxyfluoride 
crystallizes  in  plates  on  concentration  of  the  solution. 
The  salts  of  the  two  elements  should  be  purified  as  far  as 
possible  by  fractional  crystallizations. 

Experiment  2.  Preparation  of  niobic  and  tantalic 
oxides  (acids),  (Nb2O5;  Ta2O5).  (a)  Evaporate  a  solution 
of  potassium  and  niobium  oxyfluoride  to  dryness,  add  strong 
sulphuric  acid,  and  heat  until  all  the  hydrofluoric  acid 
is  expelled  and  a  solution  is  obtained.  Cool  the  solution, 
dilute  with  water,  and  boil.  Niobic  acid,  (Nb2O5),  is  pre- 
cipitated. Filter,  and  test  the  filtrate  with  ammonium 
hydroxide. 

(b)  Repeat  the  experiment,  using  a  solution  of  potas- 
sium and  tantalum  fluoride  instead  of  the  niobium  salt. 

(c)  Test  the  action  of  alkali  hydroxides  or  carbonates 
in  excess  upon  solutions  of  niobium  and  tantalum  obtained 
in  (a)  and  (b). 

Experiment  3.  Action  of  fusion  with  sodium  or  potas- 
sium hydroxide  upon  niobic  and  tantalic  acids,  (a)  Melt 
a  gram  of  sodium  or  potassium  hydroxide  in  a  hard  glass 
tube,  add  a  small  quantity  of  dry  niobic  acid,  and  heat 
again.  Note  that  the  fused  mass  is  soluble  in  water. 

(b)  Repeat  the  experiment,  using  dry  tantalic  acid 
instead  of  niobic. 


124  THE  RARER  ELEMENTS 

(c)  Acidify  portions  of  the  solutions  obtained  in  (a) 
and  (b). 

Experiment  4.  Color  tests  for  niobium,  (a)  To  separate 
portions  of  dry  niobic  oxide  (or  acid)  add  a  few  drops  of 
strong  sulphuric  acid,  and  treat  with  tannic  acid,  pyrogallic 
acid,  and  morphia,  respectively.  Note  the  brown  color. 

(b)  Repeat  the  experiment,  using  tantalic  oxide  instead 
of  niobic.     Note  the  absence  of  color. 

(c)  Try  the  action  of  metallic  zinc  upon  an  acid  solution 
containing  niobium. 

Experiment  5.  Negative  tests  of  niobium  and  tantalum. 
Note  that  hydrogen  sulphide  gives  no  precipitate,  and 
that  hydrogen  peroxide  gives  no  yellow  color  with  acid 
solutions  containing  niobium  or  tantalum. 


CHAPTER   VIII. 

MOLYBDENUM,  Mo,   96. 

Discovery.  The  name  Molybdena,  derived  from 
lead,  was  originally  applied  to  a  variety  of  substances  con- 
taining lead.  Later  the  term  was  used  to  designate  only 
graphite  and  a  mineral  sulphide  of  molybdenum  which  is 
very  similar  in  appearance  to  graphite,  and  which  was 
confused  with  it.  In  1778  Scheele,  in  his  treatise  on  molyb- 
dena  (Kong.  Vet.  Acad.  Handl.  (1778),  247),  showed  that 
it  differs  from  plumbago,  or  graphite,  in  that  on  being 
heated  with  nitric  acid  it  yields  a  peculiar  white  earth, 
which  he  proved  to  be  an  acid-forming  oxide.  This  he  called 
' '  acidum  molybdenae, ' '  and  he  supposed  the  mineral  to  be 
a  compound  of  this  oxide  with  sulphur.  In  1790  Hjelm 
(ibid.  (1790),  50;  Ann.  de  Chim.  iv,  17)  isolated  the  ele- 
ment. 

Occurrence.  Molybdenum  occurs  in  combination  in 
minerals  which  are  somewhat  widely  diffused,  though 
found  in  small  amounts: 

Contains: 
MoO3 

Molybdic  ochre  or 

Molybdite,  Fe203-3Mo03- 7iH2O 57~59% 

Powellite,  Ca(Mo,W)O4 58-59% 

Wulfenite,  PbMoO4 37-40% 

Belonesite,  MgMoCU? 78-79% 

Scheelite,  CaWO4 traces-  8% 

Molybdenite,  MoS2 60%  Mo 

125 


126  THE  RARER  ELEMENTS 

Extraction.  Molybdenum  salts  are  usually  obtained 
from  molybdenite,  the  most  abundant  ore,  though  some- 
times from  other  minerals.  The  following  processes  will 
illustrate  the  methods  employed. 

(1)  From   molybdenite.     The    mineral   is   roasted   until 
sulphur  dioxide  is  no  longer  given  off  and  the  residue  is 
yellow  when  hot  and  white  when  cold.     This  residue  is 
dissolved  in  dilute  ammonium  hydroxide,  and  the  solution 
is    evaporated    to    crystallization.     Heat    drives    off    the 
ammonia    from    the   crystals  and   leaves  the   trioxide   of 
molybdenum. 

(2)  From   molybdenite.     The    mineral   is    treated   with 
nitric  acid  (vid.  Experiment  i). 

(3)  From  wulfenite.     The  mineral  is  fused  with  potas- 
sium poly  sulphide.     Upon  extraction  with  water  the  lead 
remains  insoluble,  as  the  sulphide,  and  the  molybdenum 
goes  into  solution  as  the  sulpho  salt.     The  filtrate  is  acidi- 
fied with  sulphuric  acid,  and  the  sulphide  of  molybdenum 
is  precipitated   (Wittstein). 

The  Element.  A.  Preparation.  Elementary  molybde- 
num may  be  prepared  (i)  by  passing  dry  hydrogen  over 
either  the  trioxide  or  the  ammonium  salt  at  red  heat, 
(vid.  Experiment  6) ;  (2)  by  reducing  the  chlorides  with 
hydrogen;  (3)  by  heating  the  oxide  (MoOs)  with  "misch- 
metal";  (4)  by  heating  the  oxide  (Mo02)  with  aluminum 
(Goldschmidt  process). 

B.  Properties.  Molybdenum  is  a  gray  metallic  powder, 
which  is  unchanged  in  the  air  at  ordinary  temperatures,  but 
which,  when  heated,  passes  gradually  into  the  trioxide. 
It  is  insoluble  in  hydrochloric,  hydrofluoric,  and  dilute 
sulphuric  acids,  but  soluble  in  nitric  and  concentrated 
sulphuric  acids,  in  aqua  regia,  in  chlorine  water,  and  in 
melted  potassium  hydroxide,  and  potassium  nitrate.  Its 
specific  gravity  is  8.6. 


MOLYBDENUM.  127 

Compounds.*  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  molybdenum: 

Oxides MoO       Mo2O3    MoOa      Mo6O13   Mo3O8  MoO3 

Chlorides....  MoCl2     MoCl3     MoCl4  MoCl6 

Oxychlorides.  MoOCl* 

Mo02Cla 

Bromides.  .  .  .MoBr2    MoBr3     MoBr4 

Oxybromide. .  MoO2Brj 

Oxyiodide....  MoO3I 

Fluoride MoFfl 

Oxyfluorides  .  MoOF3 -  2KF 

+  H20 

Mo02F2.KF 
+  H2O 

Carbides MoaC  MoC 

Silicide MoSi 

Sulphides. . . .  MoS2  MoS3;  MoS4 

i 
Sulpho  salt.  . .  R2MoS4 

i 

Molybdates,  many  salts  of  the  type  RaMoO4,  as  K2MoO4 ;  CaMoO4 ;  ZnMoO4 ; 
Ag2MoO4;  etc.  The  fonnula  for  ammonium  molybdate  is  given  as 
(NH4)6Mo7024+4H2O. 

Molybdenum  trioxide  combines  with  phosphoric  pent- 
oxide  in  the  following  proportions:  P2O5:  MoO3:  :i  124, 
1:22,  1:20,  1:18,  1:16,  1:15,  1:5,  as  2K2HPO4-24MoO3  + 
3H2O;  2(NH4)3PO4-i6MoO3  +  i4H2O;  etc.  It  combines 
with  arsenic  pentoxide  as  follows :  As2O5 :  MoO3 : :  i :  20, 
1:18,  1:16,  1:6,  1:2,  as  As2O5-2oMoO3  +  27H2O; 
ioNHs-As2O6-i6MoO8  +  i4HaO;  etc. 

B.  Characteristics.  The  molybdenum  compounds  are 
known  jn  various  conditions  of  oxidation  (vid.  Typical 

*  See  also  Bailhache,  Compt.  rend,  cxxxv,  862;  Mylius,  Ber.  Dtsch.  chem. 
Ges.  xxxvi,  638;  Rosenheim,  Zeitsch.  anorg.  Chem.  xxxiv,  427;  XLVI,  311; 
XLIX,  148;  L,  320;  LIV,  97;  Grossmann,  Zeitsch.  anorg.  Chem.  XLI,  43;  Zeitsch. 
phys.  Chem.  LVT,  577;  LIV,  40;  Weinland,  Zeitsch.  anorg.  Chem.  XLIV,  81;  Sand, 
Ber.  Dtsch.  chem.  Ges.  xxxvni,  3384;  XL,  4504;  Copaux,  Ann.  chim.  phys.  [8] 
vii,  118;  Bull.  Soc.  franf.  Mineral,  xxx,  292  (Oct.  1907),  or  Chem.  Zentr.  (1908) 
I,  711;  Lancien,  Bull.  d.  Sciences  Pharmacol.  xv,  132,  or  Chem.  Zentr.  (1908) 
I,  1763;  Ruff,  Ber.  Dtsch.  chem.  Ges.  XL,  2926. 


128  THE  RARER  ELEMENTS. 

Forms),  of  which  the  highest,  (MoO3),  is  the  most  stable  and 
comprises  the  largest  number  of  salts.  The  trioxide  is 
white  to  pale  yellow,  and  dissolves  in  potassium,  sodium, 
and  ammonium  hydroxides,  forming  the  molybdates. 
When  strong  reducing  agents,  such  as  zinc  and  hydro- 
chloric acid,  act  upon  acid  solutions  of  molybdates,  the 
reduction  is  said  to  go  as  far  as  the  oxide  Mo5O7,  the  solu- 
tion passing  through  the  colors  of  the  various  oxides, 
violet,  blue,  and  black.  The  oxide  Mo5O7,  however,  is 
very  sensitive  to  oxidation,  for  it  is  changed  in  the  air  to 
the  sesquioxide  (Mo2O3)  as  soon  as  the  reducing  action  has 
ceased.  Acid  solutions  of  the  lower  oxides  give,  on  treatment 
with  the  alkali  hydroxides,  the  corresponding  hydroxides  of 
molybdenum,  Mo2O3  •  3H2O ;  MoO2  -^H2O ;  etc.  The  sulphide 
(MoS3)  is  obtained  by  treating  a  molybdate  with  ammonium 
sulphide  and  acidifying.  Its  color  is  reddish  brown. 

Estimation.*  A.  Gravimetric.  Molybdenum  is  generally 
weighed  as  the  oxide  (MoO3),  obtained  (i)  by  ignition  of 
ammonium  molybdate;  (2)  by  precipitation  of  mercury 
molybdate  and  ignition;  or  (3)  by  precipitation  of  the 
sulphide  and  conversion  into  the  oxide  by  treatment  with 
nitric  acid. 

B.  Volumetric.  Soluble  molybdates  may  be  reduced 
in  acid  solution  (i)  by  boiling  with  potassium  iodide, 
(a)  The  iodine  thus  liberated  may  be  passed  into  potassium 
iodide  and  estimated  by  standard  thiosulphate,  the  amount 
of  molybdenuir.  present  being  calculated  from  the  equation 
2MoO3+2HI  =  Mo205  +  l2  +  H20;  or,  (6)  after  the  iodine  has 
been  removed  by  boiling,  the  residual  solution  may  be 
rendered  alkaline  by  potassium  bicarbonate  and  reoxidized 
by  standard  iodine  solution  or  potassium  permanganate 
(Mauro  and  Danesi,  Zeitsch.  anal.  Chem.  xx,  507;  Fried- 

*  For  the  estimation  in  ores,  see  Low's  Technical  Methods  of  Ore  Analysis; 
Blair,  Jour,  Amer.  Chem.  Soc.  xxx,  1229. 


MOLYBDENUM.  129 

heim  and  Euler,  Ber.  Dtsch.  chem.  Ges,  xxvm,  2066; 
Gooch  and  Fairbanks,  Amer.  Jour.  Sci.  [4]  n,  156;  Gooch 
and  Pulman,  Amer.  Jour.  Sci.  [4]  xu,  449) ;  (2)  by  passing 
the  solution  over  zinc  in  a  Jones  reductor  into  a  flask 
charged  with  a  ferric  salt.  The  molybdic  acid,  reduced  to 
the  sesquioxide  (Mo203)  in  the  reductor  is  reoxidized  by 
the  ferric  salt,  and  the  ferrous  salt  formed  is  titrated  by 
permanganate  (Randall,  Amer.  Jour.  Sci.  xxiv  (1907),  313). 
See  also  under  Vanadium  a  volumetric  process  for  the 
estimation  of  vanadium  and  molybdenum  in  the  presence 
of  each  another,  page  112. 

Separation.  The  general  methods  for  the  separation 
of  molybdenum  from  the  metals  and  alkali  earths  are  the 
same  as  those  described  under  Vanadium. 

From  arsenic  and  phosphorus,  when  present  as  arsenic 
and  phosphoric  acids,  molybdenum  may  be  separated  by 
magnesium  chloride  mixture  in  ammoniacal  solution, 
ammonium-magnesium  arseniate  and  phosphate  being 
precipitated  (Gibbs,  Amer.  Chem.  Jour,  vu,  317;  Gooch, 
Amer.  Chem.  Jour,  i,  412). 

For  the  separation  from  vanadium,  vid.  Vanadium. 

From  tungsten  molybdenum  may  be  separated  (i)  by 
the  action  of  warm  sulphuric  acid  of  specific  gravity  1.37 
upon  the  oxides  (MoO3  and  WO3),  molybdic  acid  dissolv- 
ing (Ruegenberg  and  Smith,  Jour.  Amer.  Chem.  Soc. 
xxn,  772);  (2)  by  heating  the  oxides  with  hydrochloric- 
acid  gas  at  25o°-27o°  C.,  the  molybdenum  compound 
(MoO3-2HCl)  being  volatilized  (Pechard,  Compt.  rend, 
cxiv,  173;  Debray,  ibid.  XLVI,  noi);  (3)  by  precipitation 
of  the  sulphide  of  molybdenum  by  means  of  hydrogen 
sulphide  in  the  presence  of  tartaric  acid  (Rose,  Handbuch 
der  anal.  Chemie  (sechste  Auflage,  1871),  358). 


130  THE  R4RER   ELEMENTS. 


EXPERIMENTAL   WORK   ON   MOLYBDENUM. 

Experiment  i.  Extraction  of  molybdenum  salts  from 
molybdenite,  (MoS2).  Heat  5  grm.  of  the  finely  powdered 
mineral  with  nitric  acid  until  the  dark  color  has  disap- 
peared. Evaporate  to  dryness,  wash  the  residue  in  warm, 
dilute  nitric  acid,  then  in  water,  and  dissolve  it  in  am- 
monium hydroxide.  Filter,  and  evaporate  the  filtrate  to 
a  small  volume.  Ammonium  molybdate  crystallizes  out, 
which  may  be  converted  into  the  trioxide  by  careful 
ignition. 

Experiment  2.  Precipitation  of  the  sulphides  of  molyb- 
denum, (MoS2;  MoS3).  (a)  Through  a  solution  of  am- 
monium molybdate  acidified  with  hydrochloric  acid  pass 
hydrogen  sulphide.  Note  the  gradual  change  of  color 
of  the  solution,  from  red-brown  to  blue,  and  the  partial 
precipitation  of  the  sulphide  MoS2. 

(b)  To  a  solution  of  ammonium  molybdate  add  am- 
monium sulphide,  or  pass  hydrogen  sulphide  through  an 
alkaline  solution  of  a  molybdate.  Note  the  yellow-brown 
color  ((NH4)2MoS4,  typical).  Acidify  the  solution  and 
note  the  brown  precipitate  (MoS3). 

Experiment  3.  Precipitation  of  ammonium  phospho- 
molybdate  (3(NH4)20-P2O5-24(MoO3)  +  2H2O).  To  a  solu- 
tion of  ammonium  molybdate  acidified  with  nitric  acid 
add  a  drop  of  a  solution  of  sodium  phosphate,  and  warm 
gently.  Note  the  yellow  precipitate. 

Experiment  4.  Precipitation  of  the  molybdates  of 
silver,  lead,  and  barium,  (Ag2MoO4,  PbMoO4,  and  BaMoO4, 
typical).  To  separate  solutions  of  ammonium  molybdate, 
neutral  or  faintly  acid  with  acetic  acid,  add  solutions  of 
silver  nitrate,  lead  acetate,  and  barium  chloride  respec- 
tively. Note  the  solvent  action  of  nitric  acid  upon  the 
precipitates. 


EXPERIMENTAL    WORK   ON  MOLYBDENUM.  131 

Experiment  5.  Reduction  of  molybdic  acid,  (MoO3). 
(a)  Put  a  piece  of  metallic  zinc  into  a  solution  of  ammo- 
nium molybdate  and  add  hydrochloric  acid  until  the  action 
starts.  Note  the  change  in  color  of  the  solution  as  the 
reduction  proceeds  (reddish  yellow,  violet,  bluish,  black).. 
To  a  few  drops  of  the  solution  after  reduction  add  potas- 
sium or  sodium  hydroxide.  Note  the  dark-brown  pre- 
cipitate of  the  lower  hydroxides  of  molybdenum  (Mo2(OH)6, 
etc.)  mixed  with  the  hydroxide  of  zinc. 

(b)  Try  the  reducing  action  of  stannous  chloride  upon 
a  molybdate  in  solution. 

(c)  To  a  dilute  solution  of  a  molybdate  which  has  been 
treated  with  zinc  and  hydrochloric  acid,  add  some  potas- 
sium sulphocyanide  in  solution.     Note  the  red  color.     Try 
the  effect  of  adding  ether  and  shaking. 

(d)  To  a  few  drops  of  a  solution  of  a  molybdenum  com- 
pound add  a  little  strong  sulphuric  acid,  and  evaporate 
nearly   to  dryness    in  a   porcelain   dish.      Note  the  blue 
color. 

(e)  To  a  solution  of  a  molybdenum  compound  add  a 
little  diphenylcarbazid.     Note  the  indigo  blue  color. 

(/)  Try  the  effect  of  phenylhydrazin,  tannic,  gallic,  and 
pyrogallic  acids  upon  molybdenum  solutions.  Note  the 
colors — deep  red  in  the  first  instance  and  orange  to  red  in 
the  others. 

Experiment  6.  Preparation  of  elementary  molybdenun 
from  ammonium  molybdate.  Heat  a  few  grams  of  finely 
powdered  ammonium  molybdate  until  no  further  test  for 
ammonia  is  obtained  when  a  piece  of  moistened  red 
litmus  paper  is  held  over  the  substance.  Remove  the 
molybdic  trioxide  thus  obtained  to  a  Rose  crucible  and 
heat  for  some  time  in  a  current  of  hydrogen.  Note  the 
gray  powder. 


132  THE  RARER   ELEMENTS. 

TUNGSTEN,  W.     184. 

Discovery.  The  minerals  scheelite,  formerly  called 
tungsten  (i.e.  "heavy  stone"),  and  wolframite  have  long 
been  known,  but  until  about  the  middle  of  the  eighteenth 
century  they  were  regarded  as  tin  ores.  In  1781  Scheele 
(Kong.  Vet.  Acad.  Handl.  (1781),  89)  demonstrated  that 
scheelite  contained  a  peculiar  acid  which  he  named  Tung- 
stic  acid.  Two  years  later  the  brothers  D'Elhujar  showed 
the  presence  of  the  same  acid  in  wolframite. 

Occurrence.  Tungsten  is  found  combined  in  minerals 
which  are  often  associated  with  tin  ores: 

Contains 
W03. 

Wolframite,  (Fe,Mn)WO4 74-?8% 

Scheelite,  CaWO4 71-80% 

Hubnerite,  MnWO4 73~77% 

Cuprotungstite,  CuWO4 56~57% 

Cuproscheelite,  (Ca,Cu)W04 76-80% 

Powellite,  Ca(Mo,W)O4 10-11% 

Stolzite,  PbWO4 51  circa 

Raspite,  PbWO4 49     " 

Reinite,  FeWO4 - 75~76% 

Ferberite,  FeWO4 69-70% 

Yttrotantalite,  complex  niobate-tantalate 2-4% 

Tungstite,  WO 3 100  circa 

Extraction.*  Tungstic  acid  is  usually  extracted  from 
wolframite.  Any  of  the  processes  here  indicated  may  be 
followed : 

(i)  5  parts  of  the  mineral  are  fused  with  8.5  parts  of 

*  See  also  an  interesting  discussion  of  the  treatment  of  tungsten  ores,  etc., 
by  Van  Wegenen,  The  Chemical  Engineer,  Vol.  iv,  217-232  and  284-297. 


TUNGSTEN.  133 

dry  sodium  carbonate  and  1.5  parts  of  sodium  nitrate. 
On  treatment  of  the  fused  mass  with  water,  sodium  tung- 
state  is  dissolved,  and  after  filtration  tungstic  acid  is  pre- 
cipitated by  hydrochloric  acid. 

(2)  The  mineral  is  fused  with  an  equal  weight  of  calcium 
carbonate  and  one-half  of  its  weight  of  sodium  chloride, 
and  the  melt  is  treated  with  hot  water  containing  hydro- 
chloric and  nitric  acids.      The  tungstic  acid  remains  un- 
dissolved. 

(3)  The  mineral  is  decomposed  by  hydrochloric  acid 
(vid.  Experiment  i). 

The  Element.  A.  Preparation.  Elementary  tungsten 
may  be  obtained  (i)  by  heating  the  acid  in  the  presence 
of  hydrogen;  (2)  by  heating  the  chloride  (WC16)  in  the 
presence  of  hydrogen;  (3)  by  heating  the  acid  with  carbon; 
(4)  by  heating  the  nitride;  (5)  by  passing  an  electric  current 
in  vacuo  through  filaments  of  an  amalgam  of  tungsten, 
cadmium,  and  mercury,  the  cadmium  and  mercury  being 
expelled  and  the  tungsten  left. 

B.  Properties.  Tungsten  is  a  very  hard  powder,  rang- 
ing in  color  from  gray  to  brownish  black,  resembling  some- 
times tin,  sometimes  iron.  Although  unchanged  in  the  air 
at  ordinary  temperatures,  when  heated  in  finely  divided 
condition  it  ignites  and  burns  to  the  oxide  (WOs).  Its 
melting-point  is  3080°  C.  It  is  slowly  attacked  when 
heated  with  sulphuric,  hydrochloric,  or  nitric  acid,  and 
readily  attacked  by  a  mixture  of  nitric  and  hydrofluoric 
acids.  It  is  acted  upon  by  dry  chlorine  at  high  temper- 
atures ;  also  by  concentrated  boiling  potassium  hydroxide, 
with  the  formation  of  potassium  tungstate.  The  specific 
gravity  of  tungsten  is  from  16.5  to  19.1. 

Compounds.*  A.  Typical  forms.  The  following  com- 
pounds of  tungsten  may  be  considered  typical: 

*  See  also  Rosenheim,  Zeitsch.  anorg.  Chem.  LIV,  97. 


134  THE  RARER  ELEMENTS. 

t 

Oxides  * WO2  WO3 

Chlorides WC1,    WC^      WC1,  WC1« 

Oxychlorides WOC14 

W02C1, 

Bromides WBr3  WBfj 

Oxybromides WOBr4 

WOjBr, 

Iodide WI2 

Fluoride WFe 

Double  fluorides. .  KF-  WOaF+  H3O    ZnF3-  WO2F2  +  ioH2O ; 

etc. 

Carbide, WC 

Silicide WSi, 

Sulphides WS,  WS3 

Sulpho  salts R2WS4 

R2WS20, 
R2WSO3 

Tungstates,  many  salts  of  the  types  R2WO4  (normal) 

R2W4O13  (meta) 
ReW7024  (para) 

Tungstic  trioxide  (acid)  combines  with  phosphoric 
pent  oxide,  arsenic  pentoxide,  and  silicon  dioxide  in  the 
following  proportions : 

P2O5:  WO3: :  i :  22,  i :  21,  i :  20,  i :  16,  i :  12,  i :  7. 
As205:W03::i:i6,  i :  6,  1:3. 
SiO2:  WO3:  :  i:  12,  i:  10. 

B.  Characteristics.  The  compounds  of  tungsten  are 
very  similar  to  those  of  molybdenum,  and  are  known 
in  several  conditions  of  oxidation  (vid.  Typical  Forms),  of 
which  the  highest  is  the  most  stable.  The  trioxide,  (WO3), 
united  with  the  bases,  forms  the  largest  number  of  salts, 
the  tungstates.  When  acted  upon  by  reducing  agents, 
tungstic  acid  or  trioxide  may  be  reduced  to  the  dioxide, 
(WO2),  the  solution  becoming  blue,  then  brown.  When 
the  solution  of  a  tungstate  is  acidified,  tungstic  acid  is 
precipitated.  Tungstic  sulphide,  (WS3),  is  obtained  under 
the  same  conditions  as  molybdenum  sulphide,  and  is  brown. 
It  dissolves  in  ammonium  sulphide,  forming  a  sulpho  salt. 

*  Some  authorities  give  three  oxides  between  the  dioxide  and  the  trioxide, 
viz.  ,W205,  W30b,  and  W4OU. 


EXPERIMENTAL   WORK  ON   TUNGSTEN.  135 

Estimation.*  Tungsten  is  ordinarily  weighed  as  the  oxide 
(WO3),  obtained  (i)  by  igniting  ammonium  tungstate;  (2) 
by  decomposing  the  alkali  tungstates  with  nitric  acid, 
evaporating  to  dryness,  and  extracting  with  water, — tung- 
stic  acid  remaining  undissolved;  (3)  by  precipitating  mer- 
cury tungstate  and  driving  off  the  mercury  by  means  of 
heat,  leaving  the  acid  or  oxide ;  (4)  by  boiling  fused  lead 
tungstate  with  strong  hydrochloric  acid, — tungstic  acid 
being  precipitated  (Brearley,  Chem.  News  LXXIX,  64). 

Separation.  Tungsten  may  be  separated  from  the  me- 
tallic bases  and  many  other  elements  by  the  following 
process :  fusion  with  an  alkali  carbonate,  extraction  of  the 
alkali  tungstate  with  water,  acidification  with  nitric  acid, 
evaporation  to  dryness,  and  extraction  with  water, — tung- 
stic acid  remaining  undissolved. 

For  the  separation  of  tungsten  from  molybdenum  and 
vanadium,  see  those  elements.  From  arsenic  and  phos- 
phorus tungsten  is  separated  by  magnesium  mixture 
(Gooch,  Amer.  Chem.  Jour,  i,  412;  Gibbs,  Amer.  Chem. 
Jour,  vii,  337). 

From  tin  the  separation  may  be  accomplished  (i)  by 
ignition  with  ammonium  chloride,  tin  chloride  being  vola- 
tilized (Rammelsberg) ;  (2)  by  fusion  with  potassium  cyanide, 
the  tin  being  reduced  to  the  metal  and  the  tungsten  being 
converted  into  a  soluble  tungstate  (Talbot). 


EXPERIMENTAL  WORK  ON  TUNGSTEN. 

Experiment  i.  Extraction  of  tungstic  acid  from  wol- 
framite ((Fe,Mn)WO4).  Treat  5  grm.  of  the  finely  powdered 
mineral  with  about  10  cm.3 of  a  mixture  of  equal  parts  of 
hydrochloric  acid  and  water,  and  boil  as  long  as  any  action 

*  For  the  estimation  in  ores  see  Low's  Technical  Methods  of  Ore  Analysis- 


136  THE  RARER    ELEMENTS. 

seems  to  take  place.  Decant  the  solution,  add  to  the 
residue  about  10  cm.3  of  a  mixture  of  nitric  and  hydro- 
chloric acids  (aqua  regia),  and  warm.  Add  more  acid  if 
necessary,  and  continue  this  treatment  until  the  residue  is 
yellow ;  filter,  and  wash  with  dilute  hydrochloric  acid  and 
then  with  water.  Warm  the  yellow  mass  with  ammonium 
hydroxide  as  long  as  any  solvent  action  is  observed,  and 
filter.  Evaporate  the  filtrate  to  dryness  and  ignite  the 
ammonium  tungstate  to  obtain  tungstic  acid. 

Experiment  2 .  Formation  of  sodium  tungstate  and  meta- 
tungstate  (Na2W04  and  Na2W4Oi3,  typical),  (a)  Dissolve  a 
little  tungstic  acid  in  a  solution  of  sodium  carbonate. 

(b)  Dissolve  a  little  tungstic  acid  in  a  solution  of  sodium 
tungstate. 

Experiment  3 .  Precipitation  of  tungstic  sulphide  (WSa) , 
and  formation  of  the  sulpho  salt  ((NH4)2WS4).  (a)  To  a 
solution  of  sodium  or  ammonium  tungstate  add  ammonium 
sulphide,  and  acidify  with  hydrochloric  acid. 

(b)  Try  the  action  of  hydrogen  sulphide  upon  a  soluble 
tungstate. 

(c)  Try  the  action  of  ammonium  sulphide  upon  tungstic 
sulphide. 

Experiment  4.  Precipitation  of  tungstic  acid  (W03). 
Acidify  a  concentrated  solution  of  a  tungstate  with  hydro- 
chloric or  nitric  acid  and  boil.  Try  the  action  of  nitric 
and  hydrochloric  acids  upon  a  tungstate  in  the  presence  of 
tartaric  acid. 

Experiment  5.     Precipitation  of  barium,  lead,  and  silver 

tungstate s  (R2WO4,  typical).  To  separate  portions  of  a 
solution  of  sodium  tungstate  acidified  with  acetic  acid  add 
solutions  of  barium,  lead,  and  silver  salts  respectively. 

Experiment  6.  Reduction  of  tungstic  acid,  (a)  To  a 
solution  of  a  tungstate  (e.g.,  sodium  tungstate)  add  a  solu- 
tion of  stannous  chloride.  Acidify  with  hydrochloric  acid 


URANIUM.  137 

and  warm  gently,     (b)  To  a  solution  of  a  tungstate  add 
zinc  and  hydrochloric  acid  and  warm  gently. 

Experiment  7.  Salt  of  phosphorus  bead  tests.  Make  a 
bead  of  microcosmic  salt,  and  heat  it  in  the  oxidizing  and 
reducing  flames  with  a  small  particle  of  tungstic  acid. 
Try  the  effect  of  a  small  amount  of  ferrous  sulphate  upon 
the  bead  heated  in  the  reducing  flame. 


URANIUM,*  U,  238.5. 

Discovery.  Klaproth,  in  the  year  1789,  discovered  that 
the  mineral  pitch-blende,  supposed  to  be  an  ore  of  zinc, 
iron,  or  tungsten,  contained  a  "half-metallic  substance" 
differing  in  its  reactions  from  all  three  (Crell  Annal.  (1789) 
u,  387).  This  he  named  Uranium  in  honor  of  Herschel's 
discovery  of  the  planet  Uranus  in  1781.  The  body  that 
Klaproth  obtained  was  really  an  oxide  of  uranium,  as 
Peligot  showed  in  1842,  when  he  succeeded  in  isolating 
the  metal  (Ann.  de  Chim.  (1842)  v,  5). 

Occurrence.  Uranium  is  found  combined  in  a  few  min- 
erals, most  of  them  rare.  Pitch-blende  is  the  most  abun- 
dant source. 

Uraninite(pitch-bknde),UO3''UOt'PbO'N)  etc.,  contains  75-85%  (UOj-fUOj) 

Thorianite,  vid.  Uraninite,  "  12-25%  U 

Gummite,  (Pb,Ca)U3SiO12-  6H,O  ?,  "  61  -75%  UO8 

Thorogummite,  UO3-3ThO2.3SiO2-6HjO,  "  22-23%     " 

Mackintoshite,  UO2 -  3ThO2  •  3SiO2  •  3H3O,  "  21-22%  UO, 

Uranophane,  CaO  •  2UO3  •  2SiO2  •  6H2O,  "  53-67%  UO3 

Naegite,f  silicate,  "  28-29%  UO2 

Uranosphaerite,  (BiO)2U2O7-3H2O,  "  50-51%  UO3 

Walpurgite,  Bi10(UO2)3(OH)24(AsO4)4,  "  20-21%     " 

Carnotite,  K2O  •  2U2O3  •  V2O5 .  3H2O,  "  62-65%  U2O3 


*  For  a  discussion  of  radioactive  properties,  see  Chapter  III. 
t  A  Japanese  mineral,  Chem.  Zentr.  (1905)  I,  763. 


THE   RARER  ELEMENTS. 


Torbernite,  Cu(UO2)2P2O8-8H2O, 
Zeunerite,  Cu(UO2)2As2O8.8H2O, 
Autunite,  Ca(UO2)?P2O8  •  8H2O, 
Uranospinite,  Ca(  UO2)  2As2O8  •  8H2O, 
Uranocircite,  Ba(UO2)2P2O8-8H2O, 
Johannite,  sulphate,  formula  doubtful, 
Uranopilite,  CaO  •  8UO3  •  2SO3 •  25H2O, 
Thorite,  ThSiO4, 

Phosphuranylite,  (UO2)3P2O8. 6H2O, 
Trogerite,  (UO2)3As2O8.  i2H2O, 
Rutherfordite,  UO,CO,, 

Uranothallite,  2CaCO3-U(CO3)2-  ioH2O, 
Liebigite,  CaCO3-(UO2)CO3-2oH2O, 
Voglite,  complex  carbonate, 

Hatchettolite,  R(Nb,Ta)2O8-H3O, 

in 
Fergusonite,  R(Nb,Ta)O4, 

Sipylite,  complex  niobate, 

ii  in 
Samarskite,  R3R2(Nb,Ta)8O2i, 

o 

Armerodite,  complex, 
Hielmite,  complex, 

in  in 

Euxenite,  R(NbO3)3  •  R2(TiO3)3 •  |H2O, 

in  in 

Polycrase,  R(NbO3)3-  2R(TiO3)3-3H2O, 
Yttrocrasite,  complex, 


contains    57-62%  UO, 

55-56%  " 

55-62%  " 

59-6o%  " 

56-57%  " 

67-68%  " 

77-78%  " 

1-10%  « 

72-77%  " 

63-64%  « 

80-84%  " 


35-37%  UO2 

36-38%  UOS 

37%  U02 

15-16%  UOS 

o-  8%  UO, 

3-4%    " 

10-13%  U08 

16-17%  U02 

o-  5%    ' 


1-19% 

2-3% 


Extraction.     Uranium  salts  may  be  extracted  from  pitch- 
blende as  follows: 

(1)  The  mineral  is  decomposed  with  nitric  acid,   the 
acid  solution  is  evaporated  to  dryness,  and  the  mass  is 
extracted  with  water.     The  residue,  which  consists  largely 
of  lead  sulphate,  iron  arseniate,  and  iron  oxide,  is  filtered 
off,  and  on  evaporation  of  the  solution  impure  nitrate  of 
uranium  crystallizes  out,   which  may  be  purified  by  re- 
crystallization  (Peligot). 

(2)  The   mineral  is   decomposed  by  aqua   regia    (vid. 
Experiment  i). 

The  Element.     A.  Preparation.     Metallic  uranium  may 
be  obtained  (i)  by  heating  a  mixture  of  the  chloride  UC1S 


URANIUM. 


139 


with  sodium  and  potassium  chloride  in  a  porcelain  cru- 
cible surrounded  by  powdered  carbon  contained  in  another 
crucible  (Peligot) ;  (2)  by  heating  a  mixture  of  uranium 
chloride,  sodium  chloride,  and  metallic  sodium  in  a  closed 
iron  crucible. 

B.  Properties.  Uranium  is  a  somewhat  malleable  white 
metal  with  much  the  appearance  of  nickel.  Heated  in 
air  or  oxygen  to  a  temperature  of  i5o°-i7o°C.  it  burns 
to  the  oxide ;  at  ordinary  temperatures  the  oxidation  takes 
place  slowly.  Uranium  dissolves  slowly  in  cold  dilute  sul- 
phuric acid,  and  more  rapidly  upon  the  application  of  heat. 
It  is  soluble  in  nitric  and  hydrochloric  acids.  It  is  attacked 
by  chlorine  at  i5o°C.  and  by  bromine  at  240°  C.  The 
caustic  alkalies  have  no  apparent  action  upon  the  element. 
The  specific  gravity  of  uranium  is  18.6. 

Compounds.*  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  uranium: 


Carbonates.  .  . 

2UO3)            UO3 
U02C03-2K2C03 
U02C03.2(NH4)2CO, 
UC14       UC15                       U02C12 
UBr4       UBrs                        UO2Br2 
UI4 
U02(I03)2 
UF4                                       U02F2 
UOF3                                    U02F2-NaF,etc. 
US2                                      UOS2 
U02S 
U(S04)2-f-                             U02S04+3*H20 
4H20 

Chlorides  

UC1, 

UBr, 

Iodide 

lodate 

Fluorides 

UF, 

Sulphides 

US  U2S, 

Sulphates   .  .  . 

.  .  UHfSOj, 

*  See  also  Giolitti,  Gazz.  chim.  ital.  xxxv  [n],  145,  151,  162,  170;  Colani, 
Ann.  Chim.  Phys.  [8]xn,  59-144  (1907);  Mazzucchelli,  Atti  R.  Accad.  dei  Lincei, 
Roma  [5]  xvi  [n],  576;  also  Chem.  Zentr.  (1908)  i,  218;  Lancien,  Chem.  Zentr. 
(1908)  i,  1763;  Aloy,  Chem.  Zentr.  (1907)  n,  883. 

t  Other  oxides  less  well  known  than  those  given  above  are  of  the  following 
forms:  UO,  U3O,,  U3O4,  and  UO4. 


140  THE  RARER  ELEMENTS. 

'  Nitrate  ..........  UO2(NO3)2-f  6H2O 

Nitride  ..........  U3N4 

Ferrocyanides.  .  .  .  UFe(CN)fl  (UO2)3K2(FeC8Nfl)2 

Phosphates,  ortho.  UOHPO4  (UO2)5H2(PO4)4 

pyro..  (UO)2P207  (UO2)2P2O7 

meta..  UO(PO3)2  UO2(PO3)2 

Arseniate  ........  UO2HAsO4+  4H3O 

Uranates,  of  types  R2UO4,  R2U2O7,  and  R4UO8. 

B.  Charactieristics  .     Uranium  differs  from  molybdenum 
and    tungsten   in   manifesting   less   marked    acidic   quali- 
ties.     The  chief  classes  of  salts  are  the  uranyl,  in  which 
uranium    shows    its    highest    degree    of   oxidation,  corre- 
sponding to  the  oxide  U03   (e.g.,  U02C12),  and  the  ura- 
nous, of  which   the  oxide  U02    is  the   type  (e.g.,    UC14). 
The  uranyl  salts  are  the  more  stable  and  better  known. 
They  may  be  reduced  by  zinc  and  hydrochloric  acid  to 
the  lower  condition.     The  uranous  salts  are  easily  oxidized 
to   the   higher  form.     The   uranyl   salts   are,    in   general, 
yellow,    the    uranous    greenish.     The    two    conditions    of 
oxidation  may  be  further  distinguished  by  the  following 
reactions:   the    precipitate    resulting   from   the    action    of 
ammonium  sulphide  upon  uranyl  salts  is  reddish  brown,  — 
upon  uranous  salts,  light  green;  the  precipitate  resulting 
from  the  action  of  potassium  ferrocyanide  upon  uranyl 
salts  is  blood-red,  —  upon  uranous  salts   yellowish   green. 


Uranates  of  the  types  RjUC^  and  R2U2O7  are  formed  by 
the  combination  of  the  oxide  UO3  with  the  strong  bases. 

Estimation.*  A.  Gravimetric.  Uranium  may  be 
weighed  (i)  as  urano-uranic  oxide  (U3O8),  obtained  by 
precipitation  of  ammonium  uranate  by  means  of  ammonia, 
and  ignition  in  air  or  oxygen;  (2)  as  urano-uranic  oxide, 
precipitated  electrolytically  by  a  current  of  0.18  ampere 

*  Vid.  Kern,  Jour.  Amer.  Chem.  Soc.  xxni,  685.     For  the  estimation  in  ores, 
see  Low's  Technical  Methods  of  Ore  Analysis. 


URANIUM.  141 

and  3  volts  at  a  temperature  of  70°  C.  (Smith  and  Wallace, 
Jour.  Amer.  Chem.  Soc.  xx,  279;  Smith  and  Kollock,  ibid, 
xxni,  607);  (3)  as  uranous  oxide  (UO2),  obtained  by  ig- 
nition of  urano-uranic  oxide  in  a  current  of  hydrogen; 
(4)  as  the  pyrophosphate  ((UO2)2P2O7),  obtained  by  pre- 
cipitation by  means  of  ammonium  phosphate  in  the  pres- 
ence of  ammonium  acetate,  and  ignition. 

B.  Volumetric.  Uranium  may  be  estimated  volumet- 
rically  by  reduction  from  the  higher  (UO3)  to  the  lower 
(UO2)  condition  of  oxidation  by  means  of  zinc  and  sul- 
phuric acid,  and  oxidation  with  permanganate,  according 
to  the  following  formulae  (Pulman,  Amer.  Jour.  Sci.  [4] 
xvi,  229): 

(i) 
(2) 

2KHSO4  +  2MnSO4  +  H2SO4 

Separation.*  From  the  metals  which  precipitate  sul- 
phides with  hydrogen  sulphide  in  acid  solution,  uranium 
may  be  separated  by  hydrogen  sulphide.  From  iron, 
nickel,  and  other  members  of  its  own  group  it  may  be 
separated  by  ammonium  sulphide  in  the  presence  of  an 
excess  of  sodium  or  ammonium  carbonate,  the  uranium 
salt  remaining  in  solution.  From  the  alkalies  and  alkali 
earths  the  separation  may  be  accomplished  by  means  of 
ammonium  sulphide  in  the  presence  of  ammonium  chloride, 
uranium  oxysulphide  being  precipitated. 

*  Vid.  Kern,  Jour.  Amer.  Chem.  Soc.  xxin,  685.     For  the  estimation  in  oresr 
see  Low's  Technical  Methods  of  Ore  Analysis. 


I42  THE  RARER  ELEMENTS. 

EXPERIMENTAL  WORK  ON  URANIUM. 

Experiment  i .  'Extraction  of  uranium  salts  from  pitch- 
blende. Warm  5  grm.  of  pulverized  pitch-blende  with 
aqua  regia  until  the  decomposition  is  complete,  and  remove 
the  excess  of  acid  by  evaporation.  Extract  with  water  and 
boil  the  solution  a  few  minutes  with  sulphurous  acid  to 
reduce  the  arsenic  acid.  When  the  liquid  is  at  about  60°  C., 
pass  hydrogen  sulphide  through  to  the  complete  precipita- 
tion of  arsenic,  copper,  lead,  bismuth,  and  tin.  Filter, 
oxidize  the  filtrate  with  nitric  acid,  and  precipitate  with 
ammonium  hydroxide.  Treat  the  precipitate  with  hot 
concentrated  ammonium  carbonate,  filter,  and  allow  the 
filtrate  to  cool.  The  double  carbonate  of  uranium  and 
ammonium  will  separate.  A  further  precipitate,  of  crude 
ammonium  uranate,  maybe  obtained  by  boiling  the  mother- 
liquor.  Uranium  salts  may  be  extracted  from  carnotite 
by  the  method  described  under  Vanadium,  Experiment  i, 
page  114,  the  sodium  hydroxide  precipitate  being  treated 
with  hot  concentrated  ammonium  carbonate,  as  directed 
above. 

Experiment   2.     Precipitation  of  sodium,   potassium,  or 

ammonium  uranate,  (R2U2O7,  typical).  To  a  solution  of 
a  uranyl  salt  add  sodium,  potassium,  or  ammonium  hy- 
droxide. Note  the  yellow  color  of  the  precipitate  and  the 
insolubility  in  excess  of  the  reagent.  Repeat  the  experi- 
ment with  tartaric  acid  present  in  the  solution. 

Experiment  3.  Formation  of  the  soluble  double  car- 
bonates of  uranium  with  sodium  or  potassium,  and  uranium 

i 
with  ammonium,  (UO2CO3-2R2CO3)  •     (a)  To  a  solution  of 

a  uranyl  salt  add  a  solution  of  sodium  or  potassium  car- 
bonate, noting  the  first  and  the  final  effects.  Try  the  re- 
sult of  boiling,  and  of  adding  sodium  or  potassium  hydrox- 
ide to  a  separate  portion  of  the  clear  solution. 


EXPERIMENTAL    WORK  ON  URANIUM.  143 

(b)  Try  similarly  the  action  of  ammonium  carbonate 
upon  a  uranyl  salt  in  solution.     Note  the  ready  solvent 
action  of  an  excess  of  the  carbonate,  and  the  precipitation 
of  ammonium  uranate,    ((NH4)2U2O7),  on  boiling. 

(c)  To  a  solution  of  a  uranyl  salt  add  hydrogen  di- 
oxide  and    potassium  or   sodium   carbonate.       Note    the 
cherry-red  color   (Aloy). 

Experiment  4.  Precipitation  of  uranyl  ferrocyanide, 
((U02)3K2(FeC6N6)2  or  (UO2)2FeC6N6).  (a)  To  a  very 
dilute  solution  of  a  uranyl  salt  add  a  little  potassium  ferro- 
cyanide in  solution.  Note  the  red  precipitate.  This  is  a 
delicate  test  for  uranyl  salts.  The  precipitate,  which  is 
similar  in  color  to  that  formed  with  cupric  salts,  may  be 
distinguished  from  copper  ferrocyanide  by  its  decomposi- 
tion on  treatment  with  potassium  hydroxide  with  the 
formation  of  yellow  insoluble  potassium  uranate. 

(b)   Try  similarly  the  action  of  potassium  ferricyanide. 

Experiment  5.  Precipitation  of  uranyl  phosphate, 
(UO2HPO4).  To  a  solution  of  a  uranyl  salt  add  a  solution 
of  hydrogen  disodium  phosphate.  Try  the  action  of  the 
common  acids  upon  the  precipitate. 

Experiment  6.  Precipitation  of  uranyl  sulphide, 
(UO2S) .  (a)  To  a  solution  of  a  uranyl  salt  add  ammonium 
sulphide.  Note  the  dark-brown  color  of  the  precipitate, 
and  the  insolubility  in  excess  of  the  reagent. 

(b)  Try  the  action  of  hydrogen  sulphide  upon  a  uranyl  salt. 

Experiment  7.  Reduction  of  uranyl  salts .  (a)  To  a  solu- 
tion of  a  uranyl  salt  add  zinc  and  sulphuric  acid.  Note 
the  change  of  color  from  yellow  to  green. 

(b)  Bring  about  the  reduction  with  magnesium  and 
acid.  Test  the  uranous  salt  in  solution  with  potassium 
ferrocyanide  and  with  ammonium  sulphide. 

Experiment  8.  Bead  tests.  Fuse  a  little  of  a  uranium 
salt  in  a  borax  or  sodium  metaphosphate  bead.  Note  the 
yellow  color  in  the  oxidizing  flame  and  green  color  in  the 
reducing  flame. 


CHAPTER  IX. 

SELENIUM,  Se,  79.2. 

Discovery.  For  some  time  previous  to  the  discovery 
of  selenium  a  red  deposit  had  been  noticed  in  the  lead 
chambers  used  in  the  manufacture  of  sulphuric  acid  at 
Gripsholm  in  Sweden.  The  deposit  was  present  when  the 
sulphur  employed  had  been  prepared  from  pyrites  from 
Fahlun,  Sweden,  but  was  seldom  observed  when  the  sulphur 
had  been  obtained  from  other  sources.  At  first  the  un- 
known substance  was  supposed  to  be  sulphur.  When  it 
was  burned,  an  odor  as  of  decayed  cabbage  was  given  off, 
and  this  was  supposed  to  be  caused  by  the  presence  of 
tellurium  sulphide,  although  no  tellurium  could  be  ex- 
tracted from  the  material.  In  1817  Berzelius,  having 
become  a  shareholder  in  the  acid  works,  examined  the 
red  deposit,  and  in  a  short  time  he  announced  the  dis- 
covery of  a  new  element.  Because  of  its  frequent  associa- 
tion with  tellurium,  and  its  many  points  of  similarity  to 
that  element,  he  named  it  Selenium,  from  vekrjvrj,  the 
moon  (Annal.  der  Phys.  u.  Chem.  (1818)  xxix,  229). 

Occurrence.  Selenium  is  found  usually  in  combination 
with  the  metals,  as  in  the  following  minerals  : 

144 


SELENIUM.  145 

Clausthatite,  PbSe,  contains 27-28%  Se 

Tiemannite,  HgSe,  "  25-29%  " 

Guanajuatite,  Bi2Se3,  "  24-34%  " 

Naumannite,  (Ag2,Pb)Se,  "  27-30%  " 

Berzelianite,  Cu2Se,  "  39-40%  " 

Lehrbachite,  PbSe  •  HgSe,  "  24-28%  " 

Eucairite,  Cu2Se  -Ag2Se,  "  31-32%  " 

Zorgite,  vid.  Clausthalite,  "  29-34%  " 

Crookesite,  (Cu,Tl,Ag)2Se,  "  3°~33%  " 

Onofrite,  Hg(S,Se),  "  4~  6%  " 

Galenobismutite,  PbBi2S4,  "  0-14%  " 

Durdenite,  Fe2(TeO3)3  •  4H2O,         "  i-  2  %  SeO, 

Chalcomenite,  CuSeO3 •  2H2O,         "  48-49%     " 

Tellurium  (native),  Te,  "  6-  7%  Se 

Selen-sulphur,  ^Se-^S,  "  35~66%  " 

Selen-tellurium,  3X6  •  2Se,  "  29-30%  " 

It  is  found  also  in  copper  refinery  residues  and  some 
volcanic  lavas. 

Extraction.  Selenium  salts  may  be  extracted  from  flue- 
dust  by  the  following  methods: 

(1)  The    soluble    material    is    dissolved    by    treatment 
with  water,  and  the  selenium  is  extracted  from  the  residue 
by  aqua  regia  (Berzelius,  vid.  Experiment  i). 

(2)  The  seleniferous  material  is  digested  with  a  solu- 
tion of  potassium  cyanide  at  a  temperature  of  8o°-ioo°  C. 
until  the  red  color  has  changed  to  gray,  (KSeCN).     The 
selenium  goes  into  solution  and  may  be  precipitated  by 
hydrochloric    acid    (Pettersson,    Ber.    Dtsch.    chem.    Ges. 
vii,    1719). 

(3)  The  flue-dust  or  mineral  is  fused  with  sodium  car- 
bonate, and  the  selenium  is  extracted  with  water  as  sodium 
selenide  and  selenite,   (Na2Se;  Na2SeO3). 


146  THE  RARER  ELEMENTS. 

The  Element.  A.  Preparation.  Selenium  in  the  ele- 
mentary condition  may  be  prepared  by  the  action  (i)  of 
sulphur  dioxide,  zinc,  or  iron,  upon  selenious  acid  (Ber- 
zelius) ;  (2)  of  hydrochloric  acid  upon  sodium  seleno-sul- 
phite  (Pettersson) ;  (3)  of  potassium  iodide,  sodium  thio- 
sulphate,  etc.,  upon  selenious  acid. 

B.  Properties.  Like  sulphur,  selenium  is  known  in 
several  allotropic  modifications,*  and  may  be  either  soluble 
or  insoluble  in  carbon  disulphide.  In  soluble  form  selen- 
ium is  a  red  powder  which  softens  at  5o°-6o°  C.,  is  partly 
fluid  at  100°  C.  and  is  completely  fused  at  250°  C  .  After 
it  has  been  melted  it  remains  in  a  plastic  condition  for  a 
long  time  and  has  a  metallic  luster.  Its  specific  gravity 
is  4.2  to  4.3.  From  a  warm  solution  in  carbon  disulphide 
the  element  separates  in  red,  monoclinic,  crystalline  plates, 
and  from  a  cold  solution  in  orange-red  monoclinic  crys- 
tals of  different  type.  The  specific  gravity  of  these  crys- 
talline varieties  is  4.4  to  4.5.  Selenium  insoluble  in  carbon 
disulphide  may  be  obtained  by  allowing  the  element  to 
cool  very  slowly  after  it  has  been  heated  to  a  higher  tem- 
perature than  i3o°C.,  or  by  allowing  the  oxygen  of  the 
air  to  act  upon  selenides  in  aqueous  solution.  Under 
these  conditions  the  element  assumes  the  so-called  metallic 
form,  crystallizes  in  steel-gray  hexagonal  crystals,  and 
becomes  isomorphous  with  tellurium.  Selenium  in  this 
form  is  a  poor  conductor  of  electricity,  but  when  heated  to 
about  200°  C.  it  becomes  a  good  conductor.  Metallic 
selenium  melts  at  217°  C.  without  previous  softening.  Its 
specific  gravity  is  4.8. 

Selenium  boils  at  700°  C.,  yielding  a  dark-yellow  vapor 
which,  when  condensed  and  cooled,  assumes  a  form  similar 

*  For  discussions  of  these  modifications,  see  Saunders,  Jour.  Phys.  Chem. 
(1900)  iv,  423;  Marc,  Physikalisch-chemischen  Eigenschaften  des  metallischen 
Selens,  pub.  by  Leopold  Voss,  Hamburg,  1907;  de  Coninck,  Bull.  Acad.  roy. 
Belgique  (1907),  365,  or  Chem.  Zentr.  (1907)  n,  575. 


SELENIUM.  147 

to  flowers  of  sulphur;  this  is  called  flowers  of  selenium. 
The  element  is  soluble  in  sulphuric  acid,  giving  a  green 
solution,  and  is  oxidized  by  nitric  acid  to  selenious  acid, 
(H^SeOs).  It  combines  with  metals  to  form  selenides. 
When  heated  in  air  or  oxygen  it  burns  with  a  blue  flame 
and  goes  over  to  the  dioxide,  (SeCb) .  It  is  a  poor  conductor 
of  heat  and  electricity. 

Compounds.*     A.    Typical  forms.     The  following  com- 
pounds of  selenium  may  be  considered  typical : 

Oxides SeO2 

Fluorides SeF4        SeF6?  f 

Chlorides Se2Cl2         SeCl4 

SeCl3Br 

Oxychloride SeOCl2 

Bromides Se2Br2        SeBr4 

SeClBr3 

Iodides Se2I2          SeI4 

Seleno-sulphite ....  SeSO3 

Alums R2Al2(SeO4)4  +  24H2O 

Thioselenic  acid.  .  .  H2SSeO3 

Thioseleniate K2SSeO8 

Cyanides (CN)2Se 

(CN)2Se3 

H(CN)Se 

K(CN)Se 

R(CN)Se2 

Nitride N2Se 

Phosphides P4Se3 

P2Se5 

*  Rimini,  Gaz.  chim.  ital.  xxxvn  [i],  261;    Pellini,  Atti  Accad.  Lincci,  Roma 
[5]  xv  W>  629,  711;   [n],  46;   or  Review  in  Jour.  Amer.  Chem.  Soc.  xxix,  395. 
t  Ramsay,  Compt.  rend.  CXLIV,  1196;   Lebeau,  Compt.  rend.  CXLV,  190. 


148  THE  RARER  ELEMENTS. 

Selenides H2Se 

NiSe 
Ag2Se 

Na2Se2,  Na2Se3,*  Na2Se4,*  Na2Se6 
K2Se,  etc. 
Acids  (selenious  and  selenic)     H2SeO3,  H2Se04 

Salts  (selenites  and  seleniates)  R2SeO3,  R2SeO4 

B.  Characteristics.  The  compounds  of  selenium,  as  will 
appear  later,  closely  resemble  those  of  tellurium,  both 
in  structure  and  in  behavior  toward  reagents.  They 
are,  however,  rather  more  sensitive  to  the  action  of 
reducing  agents,  and  readily  precipitate  the  red  amor- 
phous variety  of  the  element,  which  tends  to  become 
black  when  heated.  Hydrogen  selenide  is  a  gas  which 

acts    like    hydrogen    sulphide    and    hydrogen    telluride, 

i 

and  precipitates  the  selenides  (R2Se).  By  the  treatment 
of  elementary  selenium  with  nitric  acid  or  aqua  regia 
and  evaporation  to  dryness,  selenious  oxide,  (Se02),  is 
formed,  which  dissolves  in  water,  forming  selenious  acid, 
(H2Se03).  By  the  action  of  powerful  oxidizing  agents, 
such  as  chlorine,  bromine,  or  potassium  permanganate, 
selenious  acid  may  be  oxidized  to  selenic  acid,  (H2SeO4), 

which  is  not  reduced  by  sulphur  dioxide.     These   acids 

i  i 

form  salts  of  the  types  R2SeO3  and  R2SeO4.     By  the  action 

of  reducing  agents,  such  as  sulphur  dioxide  or  ferrous 
sulphate,  red  amorphous  selenium  may  be  readily  pre- 
cipitated from  selenious  acid.  Two  chlorides,  (Se2Cl2; 
SeCl4),  and  the  corresponding  bromides  and  iodides  are 
known.  When  selenium  is  heated,  a  characteristic,  pene- 
trating odor  is  given  off  which  has  been  variously  described 
as  like  that  of  garlic,  decayed  cabbage,  and  putrid  horse- 

*  Mathewson,  Jour.  Amer.  Chem.  Soc.  xxix,  867. 


SELENIUM.  149 

radish.  This  odor  is  caused  by  the  formation  of  small 
amounts  of  the  hydride. 

Estimation.  A.  Gravimetric.  Selenium  is  generally 
weighed  as  the  element,  obtained  by  treating  solutions 
of  its  compounds  (i)  with  sulphurous  acid  in  hydrochloric 
acid  solution;  (2)  with  potassium  iodide  in  acid  solution 
(Peirce,  Amer.  Jour.  Sci.  [4]  i,  416);  (3)  with  hypophos- 
phorus  acid  in  alkaline  solution  (Gutbier  and  Rohn,  Zeitsch. 
anorg.  Chem.  xxxiv,  448).  Other  reducing  agents  may  be 

used. 

B.  Volumetric.     Selenium    may    be    determined    volu- 

metrically  (i)  by  oxidizing  selenious  acid  to  selenic  by 
means  of  standard  potassium  permanganate  in  sulphuric 
acid  solution,  using  an  excess  of  permanganate,  and  titrat- 
ing back  with  oxalic  acid  (Gooch  and  demons,  Amer. 
Jour.  Sci.  [3]  L,  51)  ;  (2)  by  reducing  selenic  or  selenious  acid 
by  means  of  potassium  iodide  in  hydrochloric  acid  solution, 


and  determining  by  appropriate  means  the  iodine  set  free 
(Muthmann  and  Schaefer,  Ber.  Dtsch.  chem.  Ges.  xxvi, 
1008;  Gooch  and  Reynolds,  Amer.  Jour.  Sci.  [3]  L,  254); 
(3)  by  reducing  selenic  acid  to  selenious  by  boiling  with 
hydrochloric  acid,  (SeO3  +  2HCl  =  SeO2  +  H2O  +  Cl2),  then 
passing  the  free  chlorine  into  potassium  iodide,  and  deter- 
mining the  iodine  set  free  (Gooch  and  Evans,  Amer.  Jour. 
Sci.  [3]  L,  400)  ;  (4)  by  employing  potassium  bromide  and 
sulphuric  acid  instead  of  hydrochloric  acid  in  (3)  (Gooch 
and  Scoville,  Amer.  Jour.  Sci.  [3]  L,  402)  ;  (5)  by  boiling 
a  solution  of  selenious  acid  with  sulphuric  acid,  a  known 
amount  of  potassium  iodide,  and  an  excess  of  arsenic  acid; 
the  reduction  of  the  selenious  acid  will  decrease  the  reduction 
of  arsenic  acid;  the  quantity  of  arsenious  acid  present  at 
the  close  of  the  action  may  be  measured,  after  neutral- 
ization with  potassium  bicarbonate,  by  standard  iodine 
(Gooch  and  Peirce,  Amer.  Jour.  Sci.  [4]  i,  31);  (6)  by  the 


150  THE  RARER  ELEMENTS. 

reduction  of  selenious  acid  to  elementary  selenium  by 
means  of  standard  sodium  thiosulphate  solution  in  excess 
in  the  presence  of  hydrochloric  acid, — the  excess  of  thio- 
sulphate being  determined  by  standard  iodine  solution 
(Morris  and  Fay,  Amer.  Chem.  Jour,  xvui,  703 ;  Norton, 
Amer.  Jour.  Sci.  [4]  vn,  287) ;  (7)  by  boiling  elementary 
selenium  with  ammonia  and  standard  silver  nitrate  solution, 
acidifying  with  nitric  acid,  and  determining  the  excess 
of  silver  nitrate  by  ammonium  sulpho-cyanide,  with  ferric 
alum  as  indicator;  the  quantity  of  selenium  present  is 
calculable  from  the  quantity  of  silver  nitrate  used,  as  is 
shown  in  the  following  equation:  4AgNO3  +  3Se  +  3H2O 
=  2Ag2Se  +  H2SeO3  +  4HNO3  (Friedrich,  Zeitsch.  angew. 
Chem.  xv,  852). 

Separation.  Selenium  is  separated,  together  with  tel- 
lurium, from  other  elements  by  methods  given  under 
Tellurium,  where  the  separation  of  these  two  elements 
from  each  other  is  also  discussed. 


EXPERIMENTAL  WORK   ON   SELENIUM. 

Experiment  i.  Extraction  of  selenium  from  (i)  flue- 
dust  and  (2)  seleniferous  residues  from  electrolytic  refining  of 
copper,  (i)  Treat  about  25  grm.  of  the  washed  flue-dust 
with  aqua  regia  as  long  as  any  evidence  of  action  is 
observed,  and  evaporate  to  dryness.  Extract  the  residue 
with  about  25  cm.3  of  strong  common  hydrochloric  acid, 
and  filter.  To  the  filtrate  add  about  a  gram  of  dry  ferrous 
sulphate,  and  warm  gently  if  necessary.  Filter  off  the  red 
amorphous  selenium. 

(2)  Treat  about  25  grm.  of  the  residues  with  strong 
commercial  hydrochloric  acid,  warm  as  long  as  anything 
appears  to  dissolve,  and  filter.  Precipitate  the  selenium 
as  in  (i).  Save  the  filtrate  to  be  examined  later  for  tel- 
lurium. 


EXPERIMENTAL    WORK   ON  SELENIUM.  151 

Experiment  2.  Preparation  of  selenium  dioxide,  (SeO2). 
To  a  small  amount  of  elementary  selenium  add  nitric  acid 
until  the  oxidation  is  shown  to  be  complete  by  the  cessation 
of  the  evolution  of  red  fumes  (oxides  of  nitrogen) .  Evapor- 
ate to  dry  ness  and  warm  gently.  The  white  residue  is 
selenium  dioxide.  Dissolve  this  in  a  little  water  to  form 
selenious  acid,  (H^SeOs). 

Experiment  3.  Precipitation  of  selenites.  (a)  To  a  little 
selenious  acid  add  a  few  drops  of  a  barium  salt  in  solution. 
Test  the  action  of  hydrochloric  acid  upon  the  precipitate. 

(b)  Try  the  action  of  cupric  sulphate  upon  a  little  sele- 
nious acid. 

Experiment  4.  Formation  of  selenic  acid,  (H2SeO4). 
(a)  To  a  few  cm.3  of  selenious  acid  add  first  a  small  amount 
of  sulphuric  acid  and  then  a  solution  of  potassium  per- 
manganate until  the  purple  color  is  permanent.  Bleach 
by  the  careful  addition  of  oxalic  acid. 

(6)  Pass  chlorine  gas  into  water  in  which  some  ele- 
mentary selenium  is  suspended. 

Experiment  5.  Reactions  with  selenic  acid,  (a)  To  a 
solution  of  selenic  acid  formed  as  in  4  (b)  add  a  little 
barium  salt  in  solution.  Note  the  precipitation  of  barium 
selenate  (BaSe04). 

(b)  Try  the  action  of  a  solution  of  cupric  sulphate 
upon  a  solution  of  selenic  acid.  Compare  with  3  (6). 

Experiment  6.  Reduction  of  selenic  acid  to  selenious. 
Add  to  a  given  volume  of  selenic  acid  half  as  much  strong 
hydrochloric  acid  and  boil  to  about  two  thirds  of  the  total 
volume.  Note  the  evolution  of  chlorine.  Test  by  starch 
iodide  paper. 

Experiment  7.  Precipitation  of  elementary  selenium. 
Try  the  action  of  the  following  reducing  agents  upon  dilute 
selenious  acid:  sulphur  dioxide,  hydrogen  sulphide,  acid 
sodium  sulphite,  potassium  iodide,  stannous  chloride, 
ferrous  sulphate. 


i$2  THE  RARER  ELEMENTS. 

Experiment  8.  Solvent  action  of  carbon  disulphide  upon 
selenium.  To  a  little  dry,  washed,  amorphous  selenium 
add  carbon  disulphide.  Filter,  and  allow  the  filtrate  to 
evaporate. 

Experiment  9.  Solvent  action  of  potassium  cyanide  upon 
selenium.  To  a  small  amount  of  the  red  amorphous  sele- 
nium add  a  few  cm.3  of  a  dilute  solution  of  potassium 
cyanide  (poison  !)  ,  warm  gently,  and  filter.  To  the  nitrate 
add  hydrochloric  acid. 

Experiment  10.  Behavior  of  selenium  when  subjected  to 
heat.  Heat  a  small  amount  of  elementary  selenium  on  a 
glass  rod.  Note  the  odor,  and  the  color  of  the  flame. 

Experiment  n.  Action  of  strong  sulphuric  acid  upon 
selenium.  To  a  small  amount  of  elementary  selenium  add 
a  few  cm.3  of  strong  sulphuric  acid  and  warm.  Note  the 
green  color.  Allow  to  cool  and  add  water.  Note  the 
precipitation  of  the  selenium 


TELLURIUM,  Te,   127.6.* 

Discovery.  Native  tellurium,  which  is  quite  widely 
distributed  in  small  quantities,  was  a  puzzle  to  the  early 
mineralogists.  Because  of  its  non-metallic  properties  and 
its  metallic  luster  it  was  known  as  aurum  paradoxum  and 
metallum  problematicum.  In  1782  Miiller  von  Reichen- 
stein,  after  some  careful  work  on  this  interesting  substance, 
suggested  that  a  peculiar  metal  might  be  present.  Acting 
on  the  suggestion,  Klaproth  undertook  an  investigation, 
and  in  1798  he  demonstrated  that  the  "  metal"  was  not 
identical  with  any  known  element.  He  proposed  the  name 
Tellurium  from  tellus,  earth  (Crell  Annal.  (1798)  i,  91). 

*  See  Lenher,  Jour.  Amer.  Chem.  Soc.  xxx,  741,  for  a  review  of  the  work  on 
the  homogeneity  of  tellurium.  Marckwald  in  a  recent  article  (Ber.  Dtsch.  chem. 
Ges.  XL,  4730)  claims  that  previous  atomic  weights  have  been  defective,  and  gives 
126.85  as  the  result  of  his  work. 


TELLURIUM. 


153 


Occurrence.     Tellurium  occurs  in  combination  and 
sparingly,  native. 


Petzite,  (Ag,Au)2Te,  contains. 

Goldschmidtite , 

Hessite,  Ag2Te, 

Altaite,  PbTe, 

Coloradoite,  HgTe, 

Melonite,  Ni2Te3, 

Kalgoorlite,  Hj 

Sylvanite,  (Au,Ag)Te2, 

Calaverite,  (Au,Ag)Te2-AuTe2, 

Krennerite,  (Au,Ag)Te2-AuTe2, 

Nagyagite,  Au2Pb14Sb3Te7S17, 

Tapalpite,  3Ag2(S,Te)  -Bi2(S,Te)3?, 

Tetradymite,  Bi2Te3S3, 

Grunlingite,  Bi4TeS3, 

Rickardite,  Cu2Te  •  2CuTe, 

Joseite,  formula  doubtful, 

Wehrlite,     lt 

Stutzite,  Ag4Te?, 

Tellurite,  TeO2, 

Montanite,  Bi2(OH)4TeO6?, 

Emmonsite,  formula  doubtful, 

Durdenite,  Fe2(TeO3)3-4H2O, 

Tellurium  (native),  Te, 

Selen-tellurium,  3Te2Se, 


also, 


Te 


32-35% 
59-6o% 
37-44% 
37-38% 
38-39% 
73-76% 
37-56% 
58-62% 

56-58% 
38-59% 


20-24% 

33-49% 

12-13% 

59-6o% 


29-35% 
22-23% 

79-8o% 
24-28% 
59-6o% 

47-64% 
93-97%  Te 


Te 


Tellurium  is  found  also  in  residues  from  the  electrolytic 
refining  of  copper,  and  in  flue-dust  from  smelters  working 
telluride  gold  ores. 

Extraction.  Tellurium  may  be  extracted  by  the  follow- 
ing methods : 

(i)  From  tellurium  bismuth  (tetradymite) .  The  mineral 
is  mixed  with  its  own  weight  of  sodium  carbonate,  and 


154  THE  R4RER  ELEMENTS. 

oil  is  added  until  the  mass  has  the  consistency  of  thick 
paste.  This  is  heated  strongly  in  a  well-closed  crucible 
and  then  extracted  with  water.  The  extract,  containing 
sodium  sulphide  and  sodium  telluride,  (Na2Te),  is  separated 
by  nitration  from  the  insoluble  matter  and  left  exposed 
to  the  air.  The  tellurium  separates  as  a  gray  powder.  It 
may  be  purified  by  distillation  (Berzelius). 

(2)  From  sylvanite  or  nagy agile.     The  mineral  is  treated 
with    hydrochloric    acid,    which    dissolves    the    antimony, 
arsenic,  etc.     The  residue  is   dissolved  in  aqua  regia,  the 
excess  of  acid  is  removed  by  evaporation,  and  the  gold  is 
precipitated  by  ferrous   sulphate.     After  the   removal  of 
the  gold  by  filtration  the  tellurium  is  precipitated  by  sul- 
phur dioxide   (Von  Schrotter). 

(3)  From  flue-dust  containing  tellurium.      The  material 
is  treated  with  strong  commercial  hydrochloric  acid  (vid. 
Experiment  i). 

The  Element.  A.  Preparation.  Elementary  tellurium 
may  be  obtained  (i)  by  the  action  of  reducing  agents,  as 
sulphurous  acid,  stannous  chloride,  or  hydrazine  upon  the 
salts  of  tellurium;  and  (2)  by  the  action  of  air  upon  soluble 
tellurides. 

B.  Properties.  Tellurium  is  generally  considered  a  non- 
metal,  though  Berzelius  classed  it  with  the  metals.  It  is 
known  in  two  conditions:  (i)  the  crystalline,  in  which  the 
element  has  a  luster  like  silver,  and  (2)  the  amorphous.  It 
is  unchanged  in  the  air  at  ordinary  temperatures,  but  when 
heated  in  air  or  oxygen  it  burns  with  a  green  flame,  forming 
the  dioxide  (TeO2).  It  is  not  attacked  by  hydrochloric 
acid,  but  is  acted  upon  slowly  by  concentrated  sulphuric 
acid,  with  evolution  of  sulphur  dioxide.  It  is  oxidized  by 
nitric  acid  and  aqua  regia  to  tellurous  acid,  (H2TeO3),  and 
is  dissolved  in  hot  caustic  potash,  forming  the  telluride 
and  tellurite  (K2Te;  K2TeO3).  It  combines  with  metals 
to  form  tellurides.  Like  selenium  and  sulphur,  it  is  a  poor 


TELLURIUM. 


'55 


conductor  of  heat  and  electricity.     Its  specific  gravity  is 
from  6.1   to   6.3. 

Compounds.  A.  Typical  forms.  The  following  are  typ- 
ical compounds  of  tellurium: 

Oxides TeO  TeO2  TeO8 

Chlorides TeCl2  TeCl4 

Oxychloride TeOCl2 

Bromides TeBr2  TeBr4 

Oxybromide TeOBr2 

Iodides TeI2  TeI4 

Fluoride TeF4 

Double  fluoride TeF4  •  KF 

Sulphite TeSO3 

Sulphate 2TeO2-SOa 

Sulphides  (or  sulpho  salts) .  TeS2  •  sK2S 

TeS2-Bi2S3,  etc. 
Tellurides H2Te 

As2Te3 

K2Te,  etc. 

Acids  (tellurous  and  telluric)  H2TeO3  H2TeO4* 

Salts  (tellurites  and  tellurates)  R2TeO3  R2TeO4 

B.  Characteristics.  The  compounds  of  tellurium  closely 
resemble  in  general  structure  those  of  sulphur  and  sele- 
nium. Hydrogen  telluride,  (H^Te) ,  like  hydrogen  sulphide, 

is  a   gaseous   substance,    and  it   precipitates  metallic  tel- 

i 
lurides,    (R2Te),    similar    to    the   sulphides.      Two    oxides, 

tellurous,    (TeO2),  and  telluric,    (TeO3),  are  well  known,f 
but,    unlike    the    corresponding    oxides   of   sulphur,    they 


*  Gutbier  favors  the  formula  H8TeOe.  See  also  Staudenmeier,  Zeitsch.  anorg. 
Chera.  x,  189;  Gutbier,  Zeitsch.  anorg.  Chem.  XL,  260;  Faber,  Zeitsch.  anal. 
Chera.  XLVI,  277. 

t  A  monoxide,  (TeO),  also  has  been  described. 


156  THE  RARER  ELEMENTS. 

are  very,  sparingly  soluble  in  water.  The  acids,  (H2Te03; 
H2TeO4),  may  be  formed  by  acidifying  solutions  of  the 
alkali  salts  (e.g.,  Na2TeOs  or  Na2TeO2)  which  have  been 
formed  by  the  action  of  the  alkali  hydroxides  upon 
the  oxides  (TeO2;  TeO3).  Many  tellurites  and  tellurates, 
(R2TeO3;  R2TeO4),  may  be  formed  by  treating  the  alkali 
tellurites  or  tellurates  with  soluble  salts  of  the  various 
bases.  Two  chlorides  are  known,  (TeCl2;  TeCl4),  both  of 
which  are  decomposed  by  water.  The  corresponding 
bromides  and  iodides  are  also  known.  In  general,  com- 
pounds of  tellurium  are  easily  reduced  to  the  element. 
The  'reduction,  however,  is  not  accomplished  quite  so 
readily  as  in  the  case  of  selenium  compounds. 

Estimation.*  A.  Gravimetric.  Tellurium  is  usually 
weighed  as  the  element,  obtained  by  treating  solutions 
of  tellurium  compounds  (i)  with  sulphur  dioxide;  (2) 
with  hydrazine  sulphate  in  ammoniacal  solution  (Jan- 
nasch,  Ber.  Dtsch.  chem.  Ges.  xxxi,  2377);  (3)  with  hydra- 
zine hydrate  or  its  salts  in  acid  or  alkaline  solution  (Gut- 
bier,  Ber.  Dtsch.  chem.  Ges.  xxxiv,  2724);  (4)  with  sul- 
phur dioxide  and  potassium  iodide  (Frericks,  J.  pr.  Chem. 
[2]  LXVI,  261);  (5)  with  hypophosphorus  acid  (Gutbier, 
Zeitsch.  anorg.  Chem.  xxxn,  295) ;  (6)  with  grape-sugar 
in  alkaline  solution  (Stolba,  vid.  Kastner,  Zeitsch.  anal. 
Chem.  xiv,  142);  (7)  with  acid  sodium  sulphite  or  mag- 
nesium (vid.  Experiment  i) ;  (8)  with  sulphur  dioxide  and 
hydrazine  hydrochloride  (Lenher,  Jpur.  Amer.  Chem.  Soc. 
xxx,  387). 

It  may  be  weighed  also  as  the  sulphate,  (2TeO2-SO3), 
obtained  by  treating  elementary  tellurium  with  a  mixture 

*  See  Gutbier,  Studien  iiber  das  Tellur,  pub.  by  Hirschfeld,  Leipzig,  1902; 
Mac  Ivor,  Chem.  News,  LXXXVII,  17,  162. 


TELLURIUM.  157 

of  nitric  and  sulphuric  acids  and  evaporating  (Metzner, 
Ann.  Chim.  Phys.  [7]  xv,  203). 

B.  Volumetric.  Tellurium  may  be  estimated  volumet- 
rically  (i)  by  the  reduction  of  telluric  acid  to  tellurous  by 
means  of  potassium  bromide  in  sulphuric  acid  solution, 
(H2TeO4  +  2HBr  =  H2TeO3  +  H2O  +  Br2),  the  bromine  being 
passed  into  potassium  iodide,  and  the  iodine  estimated 
by  standard  thiosulphate  (Gooch  and  Rowland,  Amer. 
Jour.  Sci.  [3]  XLVIII,  375);  (2)  by  the  reducing  action  of 
strong  hydrochloric  acid  upon  soluble  tellurates,  chlorine 
being  set  free  and  passed  into  potassium  iodide  with  libera- 
tion of  iodine,  as  above;  (3)  by  the  action  of  standard 
potassium  iodide  solution  upon  a  solution  of  tellurous 
acid  containing  twenty-five  per  cent,  by  volume  of  strong 
sulphuric  acid,  (H2TeO3  +  4H2SO4  +  4KI  =TeI4  +  4KHSO4  + 
3H2O),  tellurous  iodide  being  precipitated  as  a  black,  curdy 
mass,  which,  when  shaken,  separates  in  such  a  manner  that 
the  point  when  precipitation  ceases  can  easily  be  detected ; 
the  quantity  of  tellurium  present  is  calculable  from  the 
quantity  of  potassium  iodide  used  (Gooch  and  Morgan, 
Amer.  Jour.  Sci.  [4]  n,  271) ;  (4)  by  the  oxidation  of  tellu- 
rous acid  by  means  of  standard  potassium  permanganate 
in  acid  or  alkaline  solution  (Norris  and  Fay,  Amer.  Chem. 
Jour,  xx,  278;  Gooch  and  Peters,  Amer.  Jour.  Sci.  [4] 
viu,  122). 

Separation.*  From  the  elements  not  easily  reduced 
from  their  compounds  to  elementary  form,  tellurium  may 
be  separated  in  general  by  the  action  of  sulphur  dioxide  in 
faintly  acid  solution ;  this  precipitates  elementary  tellurium. 
From  bismuth  tellurium  is  separated  by  the  action  of 
potassium  sulphide  upon  the  precipitate  thrown  down 
from  solutions  by  hydrogen  sulphide, — the  tellurium  dis- 

*  See  Gutbier,  Studien  iiber  das  Tellur. 


158  THE  RARER  ELEMENTS. 

solving.  From  antimony  the  separation  may  be  accom- 
plished (i)  by  hydrazine  hydrate,  the  tellurium  being  pre- 
cipitated (Gutbier,  Zeitsch.  anorg.  Chem.  xxxn,  260); 
(2)  by  treatment  of  a  solution  of  sulpho-tellurite  and  sul- 
pho-antimonite  with  20%  hydrochloric  acid  in  the  pres- 
ence of  tartaric  acid,  the  tellurium  separating  out  (Muth- 
mann  and  Schroder,  Zeitsch.  anorg.  Chem.  xiv,  433).  From 
silver  tellurium  is  separated  by  hydrochloric  acid,  the 
silver  being  precipitated;  from  gold  by  the  action  of  heat 
on  the  two  metals,  tellurium  being  volatilized;  from  mer- 
cury by  the  action  of  phosphorus  acid  upon  a  cold  dilute 
hydrochloric  acid  solution  of  the  salts,  mercurous  chloride 
being  precipitated. 

From  selenium  tellurium  may  be  separated  (i)  by 
hydroxylamine  in  strong  hydrochloric  acid  solution,  the 
selenium  being  precipitated  (Jannasch  and  Muller,  Ber. 
Dtsch.  chem.  Ges.  xxxi,  2388);  (2)  by  sulphur  dioxide  in 
strong  hydrochloric  acid  solution,  selenium  being  pre- 
cipitated (Keller,  Jour.  Amer.  Chem.  Soc.  xix,  771,  and 
xxn,  241);  (3)  by  fusion  of  the  elements  with  potassium 
cyanide  in  the  presence  of  hydrogen,  tellurium  being  pre- 
cipitated when  air  is  passed  through  a  solution  of  the  melt ; 

(4)  by  the  action  of  ferrous  sulphate  (vid.   Experiment  i); 

(5)  by  the  greater  volatility  of  the  bromide  of  selenium 
(Gooch  and  Peirce,  Amer.  Jour.  Sci.  [4]  i,  181). 

EXPERIMENTAL  WORK  ON  TELLURIUM. 

Experiment  i.  Extraction  of  tellurium  from  flue-dust,  or 
from  waste  products  from  the  electrolytic  refining  of  copper. 
Treat  about  10  grm.  of  the  material  with  strong  commercial 
hydrochloric  acid  until  nothing  further  dissolves,  and  filter. 
To  a  small  portion  of  the  filtrate  add  ferrous  sulphate,  and 
warm  gently.  The  presence  of  selenium  will  be  indicated  by 
a  reddish  precipitate.  If  selenium  has  thus  been  shown  to 


EXPERIMENTAL   WORK  ON   TELLURIUM.  159 

be  present,  take  about  5  cm.3  of  the  original  filtrate,  precipi- 
tate the  selenium  and  tellurium  by  acid  sodium  sulphite  or 
by  magnesium,  wash  this  precipitate,  return  it  to  the  re- 
mainder of  the  filtrate,  and  heat  to  boiling.  The  selenium 
present  will  be  precipitated  by  the  tellurium.  Remove  the 
selenium  by  filtration  and  set  it  aside.  From  the  filtrate 
precipitate  the  tellurium  by  acid  sodium  sulphite  or  by 
magnesium  (Crane,  Amer.  Chem.  Jour,  xxxm,  408). 

To  free  the  selenium  just  obtained  from  the  excess  of 
tellurium  present  (a)  treat  the  material  with  hydrochloric 
acid  and  either  a  little  chlorine  or  a  drop  of  nitric  acid. 
Precipitate  the  selenium  by  ferrous  sulphate,  (b)  Or  w^arm 
the  material  with  a  dilute  solution  of  potassium  cyanide. 
The  selenium  goes  into  solution  as  potassium  seleno- cyanide 
and  may  be  precipitated  by  acidifying  the  solution  with 
hydrochloric  acid. 

Experiment  2.  Action  of  strong  sulphuric  acid  upon  tel- 
lurium. To  a  small  amount  of  elementary  tellurium  add  a 
few  cm.3  of  strong  sulphuric  acid  and  warm.  Note  the 
reddish- violet  color.  This  reaction  constitutes  a  good  test 
for  tellurium.  Allow  to  cool  and  add  water.  (See  Sele- 
nium, Experiment  n). 

Experiment  3 .  Preparation  of  tellurium  dioxide,  (Te02). 
To  a  small  amount  of  elementary  tellurium  add  nitric  acid, 

evaporate  to  dryness,  and  heat  gently. 

i 
Experiment  4.    Formation  of  an  alkali  tellurite,  (R2TeO3). 

Dissolve  a  little  tellurium  dioxide  in  a  solution  of  sodium 
or  potassium  hydroxide. 

Experiment  5.  Formation  of  telluric  acid,  (H^TeCU). 
To  a  solution  of  an  alkali  tellurite  add  sulphuric  acid  until 
the  precipitate  first  formed  dissolves.  Then  add  gradually 
a  solution  of  potassium  permanganate  until  no  further 
bleaching  action  is  noticed. 

Experiment  6.  Reduction  of  telluric  acid.  To  a  solu- 
tion of  telluric  acid  prepared  in  the  previous  experiment 


160  THE  RARER  ELEMENTS. 

add  a  little  potassium  bromide  and  sulphuric  acid,  and  boil. 
Note  the  evolution  of  bromine  and  the  reduction  to  tellu- 
rous  acid. 

Experiment  7.  Precipitation  of  tellurous  iodide,  (TeI4). 
To  a  solution  of  an  alkali  tellurite  add  sulphuric  acid  until 
the  precipitate  first  formed  dissolves.  Then  add  a  few 
drops  of  a  solution  of  potassium  iodide.  Note  the  black 
precipitate. 

Experiment  8.  Action  of  potassium  cyanide  upon  tellu- 
rium. Fuse  a  small  amount  of  elementary  tellurium 
with  potassium  cyanide  out  of  contact  with  the  air 
(2KCN+Te=K2Te+  (CN)2).  Extract  with  water  and  pass 
air  through  the  solution.  Note  the  precipitation  of  tellu- 
rium. 

Experiment  9.  Precipitation  of  elementary  tellurium. 
(a)  Try  the  action  of  the  following  reducing  agents  upon 
separate  portions  of  the  filtrate  obtained  in  Experiment  i 
(2),  Selenium,  or  of  any  acid  solution  containing  tellurium: 
stannous  chloride,  hydrogen  sulphide,*  sulphurous  acid, 
magnesium,  and  acid  sodium  sulphite. 

(b)  Try  the  action  of  an  alkali  stannite  upon  a  solution 
of  an  alkali  tellurite. 

Experiment  10.  Action  of  tellurium  compounds  before 
the  blowpipe.  Heat  on  charcoal  a  small  amount  of  a  tellu- 
rium compound.  Note  the  white  sublimate  and  the  green 
color  imparted  to  the  reducing  flame. 

Experiment  n.  Negative  test  of  tellurium.  Try  the 
action  of  ferrous  sulphate  upon  an  acidified  solution  of  a 
tellurite. 

*  Some  authors  give  TeS-  «is  the  constitution  of  the  precipitate  by  hydrogen 
sulphide. 


CHAPTER   X. 

PLATINUM,  Pt,  194.8. 

Discovery.  In  the  year  1750  William  Watson  presented 
to  the  Royal  Society  a  communication  from  William 
Brownrigg  in  which  was  described  a  "semi-metal  called 
Platina  di  Pinto ' '  found  in  the  Spanish  West  Indies.  Wat- 
son stated  that,  so  far  as  he  knew,  no  previous  mention  had 
been  made  of  this  substance  except  by  Don  Antonio  de 
Ulloa  in  the  history  of  his  voyage  to  South  America,  pub- 
lished in  Madrid  in  1748  (Phil.  Trans.  Roy.  Soc.  (1750) 
XLVI,  584).  However,  an  earlier  discovery  is  suggested  by 
a  statement  of  Scaliger  in  1558,  who,  in  combating  the 
opinion  of  Cardanus,  that  all  metals  are  fusible,  declared 
that  an  infusible  metallic  substance  existed  in  the  mines  of 
Mexico  and  Darien.  As  platinum  is  found  in  those  coun- 
tries, it  is  probably  the  metal  referred  to.  The  name 
Platinum  is  derived  from  the  Spanish  platina,  the  diminu- 
tive of  plata,  silver. 

Occurrence.  Platinum  occurs  alloyed  with  the  various 
metals  of  its  group — palladium,  osmium,  iridium,  etc. — and 
associated  with  other  metals,  as  iron,  lead,  copper,  titanic 
iron,  etc.  It  is  found  chiefly  in  the  Ural  Mountains,  asso- 
ciated with  chrome  iron  ore,  magnetite,  cinnabar,  diamonds, 
and  gold,  but  also  in  Brazil,  Mexico,  Borneo,  California,* 

*See  Mineral  Resources  U.  S.  (1906),  page  551. 

161 


162  THE  R4RER  ELEMENTS. 

Oregon,  Washington,  and  elsewhere.  The  Brazilian  sources 
have  recently  come  into  prominence,  and  Hussak  (Zeitsch. 
f .  Geo.  xiv,  284)  has  described  three  types  of  ore  from  that 
country.  The  first  is  similar  to  the  Uralian  platinum  in 
composition  and  associated  minerals.  The  second  contains 
no  gold  or  silver,  is  not  associated  with  magnetite  or 
chromite,  and  often  contains  as  much  as  -21%  of  palladium. 
It  occurs  with  rutile,  xenotime,  and  diamonds.  The  third 
type  is  free  from  iron,  poor  in  palladium,  and  occurs  with 
quartz  and  tourmaline.  Some  of  the  Brazilian  ores  contain 
from  73%  to  83%  of  platinum. 

Platinum  comprises  usually  from  fifty  to  eighty  per  cent, 
of  the  alloys  in  which  it  occurs.  It  is  found  combined  in 
the  mineral  sperrylite,  PtAs2,  which  contains  about  fifty- 
three  per  cent,  of  the  metal. 

Extraction.  Platinum  may  be  extracted  from  its  alloys 
by  the  following  methods : 

(1)  Fusion  process.    The  material  is  fused  with  sulphide 
of  lead.      The  iron   present   combines   with   the  sulphur. 
The  platinum  alloys  with  the  lead,  while  the  osmium  and 
iridium  do  not.     The  lead-platinum  alloy  is  separated  from 
the  mass  and  cupelled.    The  platinum  is  left  (Deville  and 
Debray) . 

(2)  Wet  process.     The  pulverized  alloy  is  heated  in  a 
porcelain  dish  with  aqua  regia  as  long  as  action  continues. 
The  solution  obtained  is  nearly  neutralized  with  calcium 
hydroxide,  and  the  iron,  copper,  rhodium,  iridium,  and  part 
of  the  palladium  separate.     After  the  removal  of  these,  the 
filtrate  is  evaporated  to  dryness  and  the  residue  is  ignited 
and  treated  with  water  and  hydrochloric  acid.     The  plati- 
num, with  traces  of  the  platinum  metals,  remains. 

The  Element.  A.  Preparation.  As  extracted  from  its 
alloys,  platinum  is  in  the  elementary  condition  (vid.  Ex- 
traction) . 

B.  Properties.  In  its  usual  form,  elementary  platinum 
is  a  grayish-white  metal  which  is  very  malleable  and 
ductile,  but  fusible  only  in  the  oxyhydrogen  blowpipe  flame 


PLATINUM.  163 

or  by  means  of  the  electric  current.  Nernst*  has  deter- 
mined its  melting-point  as  1745°  C.,  Guntzj  has  found  it 
somewhat  volatile  at  from  1000°  C.  to  1300°  C.,  and  MoissanJ 
has  volatilized  it  in  the  electric  furnace.  At  no  temperature 
is  it  oxidized  by  water  or  oxygen.  Quennessen  §  finds  it  to 
be  slightly  soluble  in  sulphuric  acid  in  the  presence  of 
oxygen,  and  Marie  ||  states  that  it  is  oxidized  by  acid  and 
alkaline  permanganate,  by  persulphates,  chlorates,  bi- 
chromates, alkaline  ferricyanide,  and  concentrated  nitric 
acid.  BerthelotT  finds  it  to  be  acted  upon  by  fuming 
hydrochloric  acid  in  the  presence  of  light  and  manganous 
chloride.  It  is  readily  soluble  in  aqua  regia.  Platinum  is 
not  acted  upon  by  sulphur  alone,  but  if  alkalies  are  present 
with  the  sulphur  some  action  takes  place.  It  is  attacked 
also  when  heated  with  potassium  nitrate.  Its  specific 
gravity  is  21.48. 

Besides  the  ordinary  form,  the  element  platinum  is 
known  to  exist  in  two  allotropic  conditions:  (i)  spongy 
platinum,  obtained  by  the  ignition  of  ammonium  chloro- 
platinate,  and  (2)  platinum-black,  obtained  by  reducing 
acid  solutions  of  platinum  salts.  In  both  of  these  forms 
platinum  condenses  gases  on  its  surface. 

Compounds.  A.  Typical  forms.  The  following  may  be 
regarded  as  typical  compounds  of  platinum: 

Oxides PtO  Pt3O4  PtO2 

Chlorides PtCl,  PtCl4 

Double  chlorides PtCl2-SrCl2+  PtCl4-  2AgCl,  etc. 

6H2O,  etc. 

Bromides PtBr2  PtBr4 

Double  bromides PtBr2-  2KBr,  etc.  PtBr4-SrBr2-f-  ioH,O 

Iodides PtI2  PtI4 

*  Nernst,  Ber.  phys.  Ges.  iv,  48. 

f  Guntz,  Bull.  soc.  chim.  [3]  xxxm,  1306. 

J  Moissan,  Compt.  rend.  CXLII,  189. 

§  Quennessen,  Compt.  rend.  CXLII,  1341. 

||  Marie,  Compt.  rend.  CXLVI,  475. 

Tf  Berthelot,  Compt.  rend,  cxxxvra,  1297. 


1 64                                     THE  RARER  ELEMENTS. 

Double  iodides PtI4  •  2KI,  etc. 

Fluorides PtFa  PtF4 

Sulphides PtS  PtS2 

Oxysulphide PtOS 

Sulpho  salts R2PtS8 

Sulphites PtSO3  •  R2SO3 ;  PtSO3  •  2RC1 

Nitrites R2(NO2)4Pt 

lodonitrites R2(NO2)2I3Pt 

Cyanide Pt(CN), 

Hydro  -  platino  -  cyanic 

acid H2Pt(CN)4 

i  ii 

Platino-cyanides R2Pt(CN)4;  RPt(CN)4,  typical 

Chloroplatinic  acid.  . .  .  H2PtCl<, 

i  ii 

Chloroplatinates R2PtClfl;  RPtCl«,  typical 


B.  Characteristics.  The  compounds  of  platinum  may 
be  divided  into  two  classes,  of  which  the  platinous  and 
platinic  oxides,  (PtO;  PtO2),  serve  as  types.  The  salts  of 
the  lower  condition  of  oxidation  are  usually  colorless  or 
reddish  brown;  they  give  with  hydrogen  sulphide  or  am- 
monium sulphide  a  dark-brown  precipitate  of  platinous 
sulphide,  (PtS),  which  is  soluble  in  ammonium  sulphide. 
They  are  decomposed  at  red  heat,  and  are  slowly  reduced 
to  metallic  platinum  when  boiled  with  ferrous  sulphate. 
The  salts  of  the  higher  condition  of  oxidation  have  a  yellow 
or  brown  color,  and  like  the  platinous  salts  they  are  de- 
composed at  red  heat.  Metals  in  general  and  organic 
matter  precipitate  platinum  from  solutions  of  platinic 
salts.  The  brownish-gray  platinic  sulphide,  (PtS2),  is  pre- 
cipitated by  the  action  of  hydrogen  sulphide  upon  a  solu- 
tion of  chloroplatinic  acid,  (H2PtCl6) ;  this  sulphide  dissolves 
slowly  in  ammonium  sulphide.  Salts  of  potassium  and 

ammonium  act  upon  chloroplatinic  acid  precipitating  the 

i 
corresponding  salts  of  that  acid,  (RgPtClg) .     When  platinous 

chloride  dissolves  in  potassium  cyanide,  platinum  potas- 


PLATINUM.  j65 

slum  cyanide  is  formed,  (K2Pt(CN)4  +  4H2O).  Many  salts 
of  this  type  are  known. 

The  platinum-ammonium  compounds  comprise  a  large 
number  of  complex  salts  *  of  the  following  types : 

(a)  The  platosamines,  PtR2(NH3)4;  PtR2(NH3)3; 
PtR2(NH3)2;  PtR2(NH3);  and  (6)  the  platinamines, 
PtR4(NH3)4;  PtR4(NH3)3;  PtR4(NH3)2;  PtR4(NH3). 

In  the  above  formulae  R  may  stand  for  OH,  Cl,  Br,  I, 
or  NO3.  These  compounds  are  formed  by  the  action  of 
ammonia  upon  the  platinum  salts. 

Potassium  iodide  gives  a  red-brown  color  to  very  dilute 
solutions  of  platinum  salts. 

Estimation.  A.  Gravimetric.  Platinum  is  generally 
weighed  as  the  metal,  obtained  (i)  by  precipitation  from 
solutions  of  compounds  by  means  of  appropriate  reducing 
agents,  such  as  formic  acid,  alcohol  in  alkaline  solution,  or 
magnesium  (Atterberg,  Chem.  Ztg.  "xxn,  538) ;  (2)  by  pre- 
cipitation of  the  sulphide  and  ignition;  (3)  by  precipitation 
of  ammonium  or  potassium  chloroplatinate,  and  decomposi- 
tion by  heat  into  the  metal  and  the  volatile  or  soluble 
alkali  chloride. 

B.  Volumetric.  Platinum  may  be  estimated  volumet- 
rically  by  reducing  the  tetrachlori.de  by  means  of  potas- 
sium iodide,  (PtCl4  +  4KI=PtI2  +  I2  +  4KCl),  and  determin- 
ing by  standard  sodium  thiosulphate  the  iodine  thus  liber- 
ated (Peterson,  Zeitsch.  anorg.  Chem.  xix,  59). 

Separation.  From  most  other  elements  platinum  may 
be  separated  by  the  action  of  reducing  agents  in  precipitat- 
ing the  metal  from  solutions.  From  the  metals  with  which 
it  is  most  often  found  associated  it  may  be  separated  by 
the  following  methods:  from  gold  (i)  by  the  action  of 
ammonium  chloride  upon  the  chlorides,  ammonium  chloro- 
platinate being  precipitated;  (2)  by  the  action  of  hydro- 
gen dioxide  and  sodium  hydroxide  upon  cold  solutions, 

*  See  Werner,  Ber.  Dtsch.  chem.  Ges.  XL,   15;    Rosenheim,  Zeitsch.  anorg. 
Chem.  XLm,  34. 


OF  THE 

UNIVERSITY 

OF 
^  C*I    ,rr> 


166  THE  RARER  ELEMENTS. 

the  gold  being  precipitated  (Vanino  and  Seeman,  Ber.  Dtsch. 
chem.  Ges.  xxxn,  1968) ;  (3)  by  the  action  of  oxalic  acid  or 
ferrous  salts,  gold  being  again  precipitated  (Hoffmann  and 
Kruss,  Zeitsch.  anal.  Chem.  xxvn,  66;  Bettel,  Chem.  News 
LVI,  133) ;  from  silver  by  heating  the  metals  with  concen- 
trated sulphuric  acid,  silver  dissolving  (Richards,  The 
Analyst,  xxvn,  265) ;  from  mercury  by  ignition  of  the 
metals,  mercury  being  volatilized. 

The  separation  of  platinum  from  the  other  platinum 
metals  is  so  involved  with  the  separation  of  these  from 
each  other  that  the  whole  subject  will  be  briefly  considered 
in  this  place.  The  following  methods  have  been  suggested. 
(i)  The  ore  is  first  treated  with  chlorine  water,  which  ex- 
tracts the  gold,  then  with  dilute  aqua  regia,  which  dis- 
solves the  platinum,  palladium,  and  rhodium.  From  this 
solution  the  platinum  is  precipitated  by  ammonium  chloride 
and  alcohol;  and  from  the  filtrate,  after  neutralization  with 
sodium  carbonate,  the  palladium  is  precipitated  as  the 
cyanide  by  mercury  cyanide.  The  residue  from  the  aqua 
regia  treatment,  containing  osmium,  iridium,  and  ruthe- 
nium, is  heated  in  air.  Osmium  is  volatilized  as  the  tetrox- 
ide,  ruthenium  sublimes  as  the  dioxide,  and  iridium  is 
left  (Pirngruber,  J.  B.  (1888),  2560;  Wyatt,  Eng.  and  Min. 
J.  XLIV,  273).  (2)  A  neutral  or  acid  solution  of  the  plat- 
inum metals,  gold,  and  mercury,  containing  chlorine,  is 
treated  with  dilute  nitric  acid  and  heated  to  boiling  in  a 
retort;  osmic  tetroxide  distils.  The  solution  is  cooled,  and 
shaken  with  ether,  which  withdraws  the  chloride  of  gold. 
After  the  removal  of  the  ether  and  gold  by  means  of  a 
separating  funnel  the  remaining  solution  is  treated  with 
ammonium  acetate  and  boiled  with  formic  acid.  This 
treatment  precipitates  all  the  metals,  which  are  then  heated 
in  a  current  of  hydrogen  to  volatilize  the  mercury.  The 
remaining  metals  are  mixed  with  sodium  chloride  and 
heated  with  moist  chlorine,  and  the  mass  is  extracted  with 
water.  If  there  is  any  residue  at  this  point  it  will  probably 


PLATINUM.  167 

be  found  to  be  iridium  and  ruthenium.  The  solution  is 
treated  with  concentrated  ammonium  chloride  as  long  as 
any  precipitate  forms.  This  precipitate  consists  of  the 
double  chlorides  of  ammonium  with  platinum,  iridium,  and 
ruthenium  respectively,  palladium  and  rhodium  remaining 
in  solution.  The  precipitate  is  dissolved  in  warm  water 
and  treated  with  hydroxylamine,  which  reduces  the  irid- 
ium and  ruthenium  to  the  condition  of  the  sesquichlorides ; 
upon  the  addition  of  ammonium  chloride  platinum  is  pre- 
cipitated as  the  chloroplatinate.  The  hydroxylamine  ni- 
trate is  evaporated,  the  residue  is  heated  in  the  presence  of 
hydrogen  and  fused  with  potassium  hydroxide  and  nitrate, 
the  mass  is  cooled  and  extracted  with  water.  Ruthenium 
dissolves  as  potassium  ruthenate,  (K2RuO4),  and  iridium 
remains  as  the  hydrate,  (Ir (OH) 3).  The  solution  contain- 
ing rhodium  and  palladium  is  evaporated  slowly  to  dryness 
in  the  presence  of  an  excess  of  ammonia,  and  the  residue 
is  dissolved  in  the  smallest  possible  amount  of  a  warm,  dilute 
ammoniacal  solution.  Upon  cooling,  the  rhodium  separates 
as  a  complex  chloride,  (Rh(NH3)5Cl3),  and  the  palladium 
remains  in  solution  (Mylius  and  Dietz,  Ber.  Dtsch.  chem. 
Ges.  xxxi,  3187).  (3)  Gold  is  removed  by  means  of  dilute 
aqua  regia.  By  treatment  with  concentrated  aqua  regia 
platinum,  palladium,  rhodium,  ruthenium,  and  part  of  the 
iridium  are  then  dissolved,  while  an  insoluble  alloy  of  os- 
mium and  iridium  in  the  form  of  grains  or  plates  remains. 
This  alloy  is  mixed  with  sodium  chloride  and  the  mixture 
is  heated  in  a  tube  with  chlorine.  Osmium  tetroxide, 
(OsO4),  distils,  and  sodium-iridium  chloride,  (Na2IrCle),  re- 
mains (Wohler,  Pogg.  Annal.  xxxi,  161).  To  the  solution  of 
the  other  platinum  metals  in  aqua  regia  ammonium  chloride 
is  added.  The  precipitate,  consisting  of  the  double  salts  of 
platinum  and  iridium,  may  by  ignition  be  converted  intc 
iridium-bearing  platinum  sponge  (used  in  the  manufacture 
of  platinum  vessels) .  To  the  filtrate  iron  or  copper  is  added, 


1 68  THE  RARER  ELEMENTS. 

which  throws  down  the  palladium,  rhodium,  and  ruthenium 
as  a  metallic  powder.  From  this  mixture  palladium  and 
the  iron  or  copper  are  dissolved  by  nitric  acid,  and  the  solu- 
tion is  then  shaken  with  mercury,  which  removes  the  palla- 
dium (von  Schneider,  Liebig  Annal.  v,  264,  suppl.).  The 
mixture  of  rhodium  and  ruthenium  remaining  is  heated  with 
sodium  chloride  at  low  redness  in  a  current  of  chlorine  and 
the  mass  is  extracted  with  water.  This  liquid  is  boiled 
with  potassium  nitrite  and  enough  potassium  carbonate 
to  make  the  solution  faintly  alkaline.  It  is  then  evaporated 
to  dryness  and  the  residue  is  pulverized  and  extracted 
with  absolute  alcohol.  The  rhodium  remains  undissolved 
as  a  double  nitrite  of  potassium  and  rhodium,  (K6Rh2(NO2)12, 
while  the  ruthenium  dissolves,  also  as  a  double  nitrite  with 
potassium,  (Ru(NO2)6-6KNO2). 

Platinum  may  be  separated  from  palladium  (i)  by  the 
action  of  warm  dilute  nitric  acid  upon  the  metals,  palladium 
dissolving;  (2)  by  the  action  of  a  strong  solution  of  am- 
monium chloride  and  alcohol  upon  the  double  potassium 
salts,  the  palladium  salt  being  soluble  (Cohn  and  Fleissner, 
Ber.  Dtsch.  chem.  Ges.  xxix,  R.  876);  from  iridium  (i)  by 
electrolysis,  the  platinum  being  precipitated  (Smith,  Amer. 
Chem.  Jour,  xiv,  435) ;  (2)  by  the  action  of  potassium 
nitrite,  sodium  carbonate,  and  boiling  water  upon  the 
double  potassium  salts,  iridium  being  reduced  to  the  con- 
dition of  the  sesquichloride  and  dissolved  (Gibbs,  Amer. 
Jour.  Sci.  [2]  xxxiv,  347) ;  from  osmium  by  heating  in  the 
presence  of  oxidizing  material,  osmium  tetroxide  being 
formed  and  volatilized;  from  ruthenium  by  treating  potas- 
sium chloroplatinate  and  the  corresponding  ruthenium 
salt  with  cold  water,  the  ruthenium  salt  dissolving  (Gibbs, 
loc.  cit.)\  from  rhodium  (i)  by  the  method  described  for 
the  separation  from  ruthenium;  or  (2)  by  the  action  of 
concentrated  solutions  of  the  alkali  chlorides  upon  these 
salts,  the  rhodium  dissolving  (Gibbs,  loc.  cit.). 


EXPERIMENTAL   WORK  ON  PLATINUM.  169 

EXPERIMENTAL  WORK  ON  PLATINUM. 

Experiment  i.  Preparation  of  chloroplatinic  acid  from 
laboratory  residues.  Boil  the  residues  consisting  of  potas- 
sium chloroplatinate,  etc.,  with  a  solution  of  sodium  car- 
bonate and  add  a  little  alcohol.  The  platinum  is  deposited 
as  a  black  powder.  Wash  the  powder,  first  with  hot  water, 
then  with  hot  hydrochloric  acid ;  dry  it,  dissolve  it  in  aqua 
regia,  and  evaporate  the  liquid  until  the  point  of  crystalli- 
zation is  reached,  adding  a  little  hydrochloric  acid  from 
time  to  time  to  remove  the  nitric  acid,  and  some  chlorine 
gas  to  convert  any  platinous  acid  to  the  platinic  condition. 

Experiment  2.  Precipitation  of  the  chloroplatinates 
of  ammonium,  potassium,  caesium,  rubidium,  and  thallium, 

(R2PtCl6).  To  separate  portions  of  a  solution  of  chloro- 
platinic acid  add  salts  of  ammonium,  potassium,  caesium, 
rubidium,  and  thallium  in  solution.  Note  the  comparative 
insolubility  of  the  new  compounds  in  water  and  in  alcohol. 

Experiment  3.  Formation  of  chloro platinous  acid.  To  a 
solution  of  chloroplatinic  acid  add  a  little  stannous  chloride. 
Note  the  darkening  of  the  color.  Add  a  little  potassium  or 
ammonium  salt  in  solution.  Note  the  absence  of  pre- 
cipitation. 

Experiment  4.  Precipitation  of  platinic  sulphide,  (PtS2). 
To  a  solution  of  chloroplatinic  acid  add  a  little  hydrogen 
sulphide,  and  warm. 

Experiment  5.  Precipitation  of  elementary  platinum. 
(a)  To  a  solution  of  a  platinum  salt  add  sodium  carbonate 
to  alkaline  reaction ;  add  also  a  few  drops  of  alcohol  and 
boil. 

(b)  Try  the  action  of  oxalic  acid  upon  a  platinum  salt 
in  solution. 

Experiment  6.  Action  of  acids  upon  platinum.  Try 
separately  the  action  of  strong  hydrochloric  and  nitric 


1 70  THE  RARER  ELEMENTS. 

acids  upon  metallic  platinum.     Note  the  effect  of  a  mixture 
of  the  two  acids  upon  the  metal. 

Experiment  7.  Test  for  platinum  in  solution.  To  a  very 
dilute  solution  of  a  platinum  salt  free  from  chlorine  add  a 
small  crystal  of  potassium  iodide.  Note  the  color. 


THE  PLATINUM  METALS 

OTHER    THAN    PLATINUM. 

Occurring  almost  invariably  associated  with  platinum 
and  usually  alloyed  with  it  are  small  quantities  of  certain 
rare  elements  which,  together  with  platinum,  comprise 
the  group  of  so-called  Platinum  Metals.  These  very  rare 
elements  are  the  following: 

Palladium,   Pd,    106.5  Osmium,   Os,    191 

Iridium,  Ir,  193  Rhodium,  Rh,  103 

Ruthenium,  Ru,   101.7 

Discovery.  In  1803,  in  the  course  of  the  purification 
of  a  considerable  quantity  of  crude  platinum,  Wollaston 
isolated  a  new  metal  which  he  named  Palladium,  in  honor 
of  the  discovery  by  Olbers  of  the  planetoid  Pallas.  The  newly 
discovered  element  was  brought  to  the  attention  of  scien- 
tists anonymously  through  a  dealer's  advertisement,  which 
offered  "palladium  or  new  silver"  for  sale.  Much  dis- 
cussion as  to  the  nature  of  the  substance  ensued,  Chenevix, 
in  particular,  holding  it  to  be  an  alloy  of  platinum  and  mer- 
cury. In  1805  Wollaston  confessed  to  the  discovery  and 
naming  of  the  metal  (Phil.  Trans.  Roy.  Soc.  (1803)  xcni, 
290;  ibid.  (1805)  xcv,  316;  Nicholson's  J.  (1805)  x,  204). 

The  same  year  that  palladium  was  discovered,  Smithson 
Tennant  found  that '  *  the  black  powder  which  remained  after 
the  solution  of  platina  did  not,  as  was  generally  believed, 
consist  chiefly  of  plumbago,  but  contained  some  unknown 


THE  PLATINUM  METALS.  171 

metallic  ingredients."  In  1804  he  presented  to  the  Royal 
Society  as  the  result  of  his  study  a  communication  announc- 
ing the  discovery  of  two  new  metals,  Iridium,  named ' '  from 
the  striking  variety  of  colors  which  it  gives  while  dissolving 
in  marine  acid, ' '  and  Osmium,  so  called  because  of  the 
penetrating  odor  (007*77,  odor)  of  the  acid  obtained  from 
the  oxidation  of  the  element  when  it  is  heated  in  a  finely 
divided  condition  (Phil.  Trans.  Roy.  Soc.  (1804)  xciv,  411). 

A  few  days  after  Tennant's  communication,  Wollaston 
announced  the  discovery  of  an  element  in  the  * '  fluid  which 
remains  after  the  precipitation  of  platina  by  sal  ammoniac, ' ' 
and  suggested  the  name  Rhodium  (podios,  rose-like),  "from 
the  rose  color  of  a  dilute  solution  of  the  salts  containing 
it"  (Phil.  Trans.  Roy.  Soc.  (1804)  xciv,  419). 

In  1826  Osann  claimed  the  discovery  of  three  new  ele- 
ments in  platinum  alloys.  These  he  named  Ruthenium, 
Polinium,  and  Pluranium  (Pogg.  Annal.  vm,  505;  Amer. 
Jour.  Sci.  xvi,  384).  Later  he  withdrew  the  claim.  In 
1844  Claus  found  that  there  was  an  unknown  metal  in  the 
mixture  of  substances  which  had  been  called  by  Osann 
"ruthenium  oxide,"  and  for  it  he  retained  the  name 
ruthenium,  derived  from  Ruthenia,  i.e.  Russia,  where  the 
substance  was  first  found  (Pogg.  Annal.  LXIV,  192,  208; 
Amer.  Jour.  Sci.  XLVIII,  401). 

Occurrence.  The  •  very  rare  platinum  metals,  as  has 
been  already  stated,  are  found  in  general  in  platinum- 
bearing  material.  Palladium  and  iridium  sometimes  occur 
native;  the  others  always  in  alloys  or  in  combination. 


%  Pd  %  Os  it  Ir 

Native  platinum  contains  0.1-3.1  traces-4 . 2       traces          o .  2-3 . 4 

circa  7 

0.2-6 
65 


'  '        iridium 

0.4-0.8                   27-76.8 

Palladium  gold 

"             5-io 

Iridosmine 

17-48           40.7     0.5-12.3 

Laurite,  RuS2 

circa  3 

Rhodium  gold 

34-43 

Extraction. 

For  methods  of    extraction  of 

the  very 


172  THE  RARER  ELEMENTS. 

rare  platinum,  metals  see  Extraction  and  Separation  of 
Platinum. 

The  Elements.  I.  PALLADIUM.  A.  Preparation.  Ele- 
mentary palladium  may  be  obtained  (i)  by  heating  the 
potassium  double  chloride  with  hydrogen  (Roessler) ;  (2)  by 
heating  the  iodide  with  hydrogen;  and  (3)  by  heating  the 
chloride  or  cyanide. 

B.  Properties.  Palladium  is  a  ductile,  malleable,  white 
metal  which  looks  like  platinum.  It  may  be  partially 
oxidized  before  the  oxyhydrogen  blowpipe.  It  is  soluble 
in  strong  nitric,  hydrochloric,  and  sulphuric  acids,  and 
easily  soluble  in  aqua  regia.  It  fuses  at  a  lower  temperature 
than  any  other  of  the  platinum  metals  (154.1°  C.,  Nernst). 
In  spongy  form  it  has  the  power  of  absorbing  gases.  Its 
specific  gravity  is  11.4-11.8.  It  may  be  distinguished 
from  the  other  platinum  metals  by  the  comparative  ease 
with  which  it  dissolves  in  nitric  acid. 

II.  OSMIUM.  A.  Preparation.  The  element  osmium 
may  be  prepared  ( i )  by  heating  the  amalgam  in  the  presence 
of  hydrogen  (Berzelius) ;  (2)  by  heating  the  sulphide  in  a 
closed  coke  crucible ;  (3)  by  passing  the  vapor  of  the  tetroxide 
mixed  with  carbon  dioxide  and  carbon  monoxide  through  a 
heated  porcelain  tube;  (4)  by  passing  the  vapor  of  the 
tetroxide  through  a  heated  porcelain  tube  containing  finely 
divided  carbon  (Deville  and  Debray) ;  (5)  by  igniting 
osmyldiamine  chloride,  (Os(NH3)402CL),  in  a  current  of 
hydrogen. 

B.  Properties.  Osmium,  the  heaviest  of  the  platinum 
metals,  is  a  bluish  substance,  crystals  of  which  are  harder 
than  glass.  In  the  compact  form  it  is  insoluble  in  all  acids 
and  in  aqua  regia,  and  is  rendered  soluble  only  by  fusion 
with  nitrates.  The  amorphous  modification  is  slowlv 
soluble  in  nitric  acid  and  in  aqua  regia.  The  specific  gravity 
of  the  compact  and  amorphous  modifications  is  21.3;  of 


THE  PLATINUM  METALS.  173 

the  crystalline  form  22.4.  Osmium,  like  the  other  platinum 
metals,  has  been  volatilized  in  the  electric  furnace  (Moissan, 
Compt.  rend.  CXLII,  189) ;  it  is,  however,  the  most  refractory 
of  the  group. 

III.  IRIDIUM.     A.  Preparation.      Metallic  iridium  may 
be  obtained   (i)   by  heating  indium-ammonium   chloride, 
and  (2)  by  heating  indium-potassium  chloride  with  sodium 
carbonate. 

B.  Properties.  Iridium,  a  hard,  brittle  metal,  resembles 
silver  and  tin  in  appearance.  The  ignited  form  is  insoluble 
in  all  acids  and  in  aqua  regia.  The  element  is  partially 
oxidized,  however,  by  fusion  with  sodium  nitrate,  and  the 
fused  mass  may  be  dissolved  by  boiling  it  with  aqua  regia. 
In  spongy  form  iridium  has  the  specific  gravity  of  15.86; 
after  fusion  the  specific  gravity  is  21-22. 

IV.  RHODIUM.     A.  Preparation.      Elementary  rhodium 
may  be  prepared  (i)  by  heating  ammonium -rhodium  ses- 
quichloride;    (2)    by  heating  rhodium   sesquichloride  and 
sodium  in  a  current  of  hydrogen;  (3)  by  heating  rhodium 
sulphide  to  a  white  heat;   and  (4)   by  allowing  reducing 
agents,  as  formic  acid,  zinc,  iron,  alcohol  in  alkaline  solu- 
tion, hydrogen,  etc.,  to  act  upon  soluble  salts. 

B.  Properties.  Rhodium  is  a  grayish-white  metal  which 
has  the  appearance  of  aluminum.  When  pure  it  is  almost, 
absolutely  insoluble  in  acids  and  in  aqua  regia,  but  when 
alloyed  it  may  be  dissolved  in  aqua  regia.  It  is  fusible 
before  the  oxyhydrogen  blowpipe,  but  more  difficultly 
than  platinum.  It  has  the  property  of  absorbing  hydrogen. 
Of  all  the  platinum  metals  rhodium  is  most  easily  attacked 
by  chlorine.  Its  specific  gravity  is  11-12. 

V.  RUTHENIUM.     A.  Preparation.     The  element  ruthe- 
nium may  be  obtained  (i)  by  heating  the  oxide  with  illu- 
minating-gas, and    (2)  by  heating   ruthenium-ammonium- 
mercury  chloride. 

B.  Properties.  Ruthenium  is  a  hard,  brittle  metal,  dark 
gray  to  black  in  color.  It  is  almost  completely  insolu- 


174 


THE  RARER  ELEMENTS. 


ble  in  acids  and  in  aqua  regia;  and  osmium  alone,  of  all 
the  platinum  metals,  is  more  difficultly  fusible.  It  may 
be  slightly  oxidized  by  fusion  with  caustic  potash  and 
oxidized  to  a  greater  degree  by  fusion  with  potassium 
nitrate.  The  specific  gravity  of  the  crystalline  form  is 
12.26 ;  of  the  melted  form  11.4;  and  of  the  porous  form  8.6. 
Compounds.  A.  Typical  forms.  The  following  com- 
pounds of  the  platinum  metals  may  be  considered  typical: 


Chlorides. 

PdO 
Pd203t 
PdO2 

PdCl 

OsO 
OsA 
Os02 
(Os03)* 
OsO4 

IrO? 
Ir,O3 
Ir02f 

RhO 
Rh2O3 
RhO2 

RuO 
Ru203 
RuO2 
(RuOj)* 
RuO4 
(Ru207)* 

Bromides 

PdCl2 

PdCl4 
PdBr, 

OsCl2 
OsCl3 
OsCl4 

IrCl2 
Ir.Cle 
IrCl4 

RhCl, 
Rh,Cl, 

RuCl2 
Ru2Cl« 
RuCl« 

Iodides 

PdBr4 
Pdl. 

Ir2Bre 
IrBr4 

Sulphides.  . 

....Pd2S 
PdS 

PdS, 

OsS, 
OsS4 

Ir2I6? 
M* 

IrS 
Ir2S, 
IrS2 

Wa 

RhS 
Rh2S, 

Ru,I, 

Ru2Ss 
RuS2 
RuS3 

Sulphates PdSO4 


Sulphites PdSOj-          OsSO, 

3Na2S03 

Sulpho  salts.  .  .  .  R2Pd3S4 
R2PdS3 


Ir2(S03)8       Rh2(S03), 


*  This  oxide  is  known  only  in  combination. 

t  Wohler,  Zeitsch.  anorg.  Chem.  LVII,  323,  398. 

J  Also  alums,  see  Marino,  Zeitsch.  anorg.  Chem.  XLII,  213;  complex  oxalates, 
see  Gialdini,  Atti  R.  Accad.  dei  Lincei,  Roma  [5]  xvi  [n],  648,  or  Chem.  Zentr. 
(1908)  I,  107. 


THE  PLATINUM    METALS. 


175 


Nitrites  ........  Pd(NO2)2  •  2KNO2 


Nitrates  .......  Pd(NO3), 

Acids  and  corre- 

spond'g  salts..  .  H2PdCl4;  f 

R2PdCl, 


Ir2(N02)8.     Rh2(N02)8. 
6HNO2          6RNO2 

Rh2(NO3)0 


Ru2(NO2V 
6RNO2 


I^OsCl,; 

RsOsCl, 
H2PdClfl;       H2OsClG; 

R2PdCl6         R2OsCl6      R,!^!, 


R4RhCl7; 
R3RhCl8  § 


H2RuCl« 


Characteristics.  I.  PALLADIUM.  The  compounds  of  pal- 
ladium resemble  those  of  platinum,  both  in  form  and 
in  general  characteristics.  As  in  the  case  of  platinum, 
palladium  combines  with  ammonia  to  form  complex  salts, 
and  an  oxide,  (PdO),  forms  salts  with  sulphur  dioxide  and 
with  nitrogen  trioxide,  (N2O3).  In  general  the  salts  are 
quite  easily  reduced  to  the  metal  by  heating ;  their  solutions 
resemble  a  solution  of  platinic  chloride  in  color.  Two 
oxides,  (PdO;  PdO2),  are  well  known,  of  which  the  lower 
forms  the  more  stable  compounds.  These  compounds  give 
a  yellowish-brown  precipitate  with  potassium  hydroxide. 
Solutions  of  palladium  salts  give  with  mercuric  cyanide  a 
yellowish- white  precipitate,  (Pd(CN)2) ;  with-  potassium 
iodide  a  black  precipitate,  (PdI2),  which  is  soluble  in  excess 
of  the  reagent ;  and  with  hydrogen  sulphide  also  a  black 
precipitate,  (PdS),  insoluble  in  ammonium  sulphide. 


*  See  also  Wintrebert,  Compt.  rend.  CXL,  585. 

f  See  also  Gutbier,  Ber.  Dtsch.  chem.  Ges.  xxxvm,  23;  xxxix,  4134;  XL, 
690;  Zeitsch.  anorg.  Chem.  XL v,  166,  243;  XLVII,  23. 

t  See  also  Howe,  Jour.  Amer.  Chem.  Soc.  xxvi,  543,  942;  Gutbier,  Zeitsch. 
anorg.  Chem.  XLV,  166,  243;  XLVII,  23;  Ber.  Dtsch.  chem.  Ges.  xxxvin,  2105, 
2885. 

§  See  also  Gutbier,  Ber.  Dtsch.  chem.  Ges.  XLI,  210. 


176  THE  RARER  ELEMENTS. 

Mercuric  cyanide  and  potassium  iodide  are  often  used  as 
tests  for  palladium. 

II.  OSMIUM.     Compounds  of  osmium  are  known  in  five 
degrees    of    oxidation.     The    lowest    three    oxides,    (OsO ; 
Os2O3;  OsO2),  are  basic  in  character,  the  fourth,*  (OsO3), 
is  acidic,  and  the  fifth,  (OsO4),  is  also  acidic,  but  it  forms 
no  salts.     Three  chlorides,  (OsCl2 ;  OsCl3 ;  OsClJ ,  are  known, 

corresponding  to  the  lowest  oxides.     The  metals  sodium, 

i 

potassium,  and  barium  form  salts  of  the  type  R2OsO4. 
These  salts  are  readily  decomposed,  especially  by  acids,  and 
form  the  dioxide  and  the  tetroxide.  When  osmium  com- 
pounds are  heated  in  the  air  with  oxidizing  agents,  or  are 
melted  with  potassium  nitrate,  the  tetroxide  is  obtained. 
It  is  volatile  when  heated,  highly  corrosive,  and  disagree- 
able like  chlorine.  It  is  soluble  in  water  and  is  reduced 
by  reducing  agents.  From  potassium  iodide  it  frees  iodine, 
and  with  formic  acid  to  which  potassium  hydroxide  has 
been  added  it  gives  a  violet  color.  With  ferrous  sulphate 
it  precipitates  black  osmium  hydroxide,  (Os(OH)4),  and 
with  hydrogen  sulphide  it  brings  down  the  brownish-black 
sulphide  (OsS4),  which  is  insoluble  in  ammonium  sulphide. 

III.  IRIDIUM.     The  compounds  of  indium  exist  chiefly 
in  three  conditions  of  oxidation,  of  which  the  di-,  tri-,  and 
tetrachlorides    may    serve    as    types,   (IrCl2;  Ir2Cl6;  IrClJ. 
The  iridium  compounds  are  reduced  to  the  metal  when 
mixed  with  sodium  carbonate  and  heated  in  the  outer 
flame   of   a   Bunsen  burner.     The  alkali  double  chlorides 
with  iridous  chloride,  (IrCl2),  are  in  general  soluble  in  water. 
Solutions  of  iridium  salts  in  the  lowest  condition  of  oxida- 
tion give  with  potassium  hydroxide  a  greenish  precipitate, 
which  tends   to   darken  when  boiled.     Reducing  agents, 
as  sodium  formate,  precipitate  metallic  iridium,  and  hydro- 
gen sulphide  precipitates  from  the  warmed  solution  a  brown 

*  Known  only  in  salts. 


THE  PLATINUM  METALS.  177 

iridium  sulphide  (IrS).  By  means  of  oxidizing  agents, 
solutions  of  iridous  salts  may  be  converted  into  the  high- 
est condition  of  oxidation.  From  solutions  of  this  latter 
type  potassium  hydroxide  throws  down  a  dark-brown  pre- 
cipitate of  potassium -iridium  chloride,  (IrCl4'2KCl),  and 
hydrogen  sulphide  precipitates  slowly  a  brown  sulphide, 
(Ir2S3).  The  greater  number  of  iridium  compounds  are 
easily  reduced  by  hydrogen  on  being  heated.  The  pres- 
ence of  iridium  may  be  detected  by  the  blue  color  de- 
veloped when  the  compound  is  heated  with  concentrated 
sulphuric  acid  to  which  ammonium  nitrate  has  been  added. 

IV.  RHODIUM.     Although  three  oxides  of  rhodium  are 
known  and  described,   (RhO;  Rh2O3;  RhO2),  salts  of  only 
two  conditions  of  oxidation  are  generally  found;  of  these 
the  di-  and  trichlorides  are  types,  (RhCl2;  Rh2Cl6).     From 
solutions  of  rhodium  salts  reducing  agents  precipitate  the 
metal.     Hydrogen  sulphide  throws  down  from  a  cold  solu- 
tion the   sulphide   (Rh2S3),   and  from  a  hot  solution  the 
sulphydrate  (Rh2(SH)6).     The  insolubility  of  the   double 
chloride  of  rhodium  and  sodium,  (Rh2Cl'6NaCl),  in  water, 
and   of   the   double   nitrate   of   rhodium   and   potassium, 
(K6Rh6(NO2)12),  in  alcohol  is  made  use  of  in  separating  the 
metal  from  the  other  members  of  the  group.     Rhodium 
is  detected  in  the  presence  of  the  other  platinum  metals  by 
the  yellow  solution  obtained  after  fusion  with  potassium 
acid  sulphate  and  the  change  of  color  to  red  upon  the  ap- 
plication of  hydrochloric  acid. 

V.  RUTHENIUM.     In  the  variety  of  conditions  of  oxida- 
tion in  which  they  are  found,  the  compounds  of  ruthenium 
resemble  those  of  osmium.     The  lowest  three  oxides  are 
basic  in  character,  (RuO;  Ru2O3;  RuO2),  and  form  salts  of 
which  the  three  chlorides,  (RuCl2 ;  Ru2Cl6 ;  RuCl4),are  typical. 

The  trioxide,  (Ru03),  is  known  only  in  combination,  where 

i 
it  acts  as  an  acid  and  forms  salts  of  the  type  R2RuO4. 


178  THE  RARER    ELEMENTS 

Another  oxide,  (Ru2O7),  known  only  in  combination,  forms 

i 
salts  represented  by  the  formula  RRuO4.     The  tetroxide 

(RuO4)  is  volatile  and  similar  to  the  corresponding  oxide  of 
osmium  in  its  chemical  behavior;  it  has  a  characteristic 
odor.  A  solution  of  the  trichloride,  (Ru2Cl6),  throws  out, 
when  heated,  a  dark  precipitate  which  is  generally  sup- 
posed to  be  an  oxychloride;  this  precipitate  is  held  in 
suspension  in  the  liquid,  and  gives  a  pronounced  coloration, 
even  in  very  dilute  solutions.  Hydrogen  sulphide,  acting 
upon  solutions  of  ruthenium  salts,  precipitates  a  mixture 
of  sulphides,  oxysulphides,  and  sulphur;  this  mixture  is 
brown  or  black,  and  may  contain  one  or  more  of  the  sul- 
phides Ru2S3,  RuS2,  and  RuS3. 

Estimation.  The  platinum  metals  are  weighed  in  the 
elementary  condition,  obtained  as  described  under  Prepara- 
tion of  the  various  metals. 

Osmium  may  be  determined  volumetrically  by  causing 
potassium  iodide  to  act  upon  the  tetroxide  in  the  presence 
of  dilute  sulphuric  acid,  (OsO4  +  4KI  +  2H2SO4  =  OsO2  + 
2K2SO4  +  4l  +  2H2O),  and  estimating  by  means  of  sodium 
thiosulphate  the  iodine  thus  liberated  (Klobbie,  Chem. 
Central-Blatt  (1898)  n,  65  (abstract).  The  gravimetric 
methods  for  the  determination  of  osmium  have  recently 
been  studied  by  Paal  (Ber.  Dtsch.  chem.  Ges.  XL,  1378) 
and  found  unsatisfactory. 

Separation.  The  separation  of  the  platinum  metals 
has  been  considered  under  Platinum.  The  following  are 
additional  references:  Gibbs,  Amer,  Jour.  Sci.  [2]  xxxi,  63; 
xxxiv,  341;  xxxvn,  57;  Forster,  Zeitsch.  anal.  Chem. 
v,  117;  Bunsen,  Liebig  Annal.  CXLVI,  265;  Chem.  News 
xxi,  39 ;  Deville  and  Debray,  Compt.  rend.  LXXXVII,  441 ; 
Chem.  News  xxxvni,  188;  Wilm,  Ber.  Dtsch.  chem.  Ges. 
xvi,  1524;  Leidie,  Compt.  rend,  cxxxi,  888;  Bull.  Soc. 
Chim.  d.  Paris  [3]  xxvn,  179. 


EXPERIMENTAL   WORK   ON   THE  PLATINUM  METALS.       179 


EXPERIMENTAL  WORK  ON  THE  PLATINUM 
METALS. 

Experiment  i.  Precipitation  of  palladous  iodide,  (PdI2). 
To  a  solution  of  a  palladium  salt  add  a  little  potassium 
iodide  in  solution. 

Experiment  2.  Precipitation  of  palladous  sulphide, 
(PdS).  (a)  Pass  hydrogen  sulphide  through  a  solution  of 
a  palladous  salt. 

(b)  Try  the  action  of  ammonium  sulphide  upon  a  palla- 
dous salt  in  solution. 

Experiment  3.  Precipitation  of  ike  hydroxide  or  basic 
salt.  To  a  solution  of  a  palladous  salt  add  a  little  sodium 
hydroxide  or  carbonate  in  solution. 

Experiment  4.  Precipitation  of  palladous  cyanide.  To 
a  solution  of  a  palladous  salt  add  a  solution  of  mercuric 
cyanide.  Try  the  action  of  potassium  cyanide  and  ammo- 
nium hydroxide  upon  the  precipitate. 

Experiment  5.  Action  of  ammonium  chloride  upon 
palladous  aud  palladic  chlorides.  (a)  To  a  solution  of 
palladous  chloride  add  ammonium  chloride. 

(b)  Saturate  a  solution  of  palladous  chloride  with 
chlorine  and  add  ammonium  chloride.  The  palladic  salt 
(Pda6)(NH4)2  is  insoluble. 

Experiment  6.  Precipitation  of  elementary  palladium. 
To  a  solution  of  a  palladium  salt  add  sodium  carbonate 
to  alkaline  reaction;  add  also  a  few  drops  of  alcohol  and 
boil. 

Experiment  7.  Action  of  nitric  acid  upon  palladium. 
Try  the  action  of  nitric  acid  upon  a  small  piece  of  metallic 
palladium. 

Experiment  8.  Precipitation  of  osmium  sulphide,  (OsS^. 
(a)  To  a  solution  of  osmium  tetroxide  acidified  with  hydro- 
chloric acid  add  a  little  hydrogen  sulphide. 


l8o  THE  RARER  ELEMENTS. 

(b)  Try  the  action  of  ammonium  sulphide  upon  the 
tetroxide  in  solution. 

Experiment  9.  Formation  of  potassium  osmate,  (K^OsO*) . 
To  a  solution  of  osmium  tetroxide  add  a  solution  of  potas- 
sium hydroxide.  Note  the  yellow  color. 

Experiment  10.  Action  of  reducing  agents  upon  osmium 
tetroxide.  Try  the  action  of  an  alkali  sulphite,  formic  acid, 
and  tannic  acid,  respectively,  upon  a  solution  of  osmium 
tetroxide. 

Experiment  n.  Action  of  osmium  tetroxide  upon  hy- 
driodic  acid.  To  a  solution  of  osmium  tetroxide  add  a  little 
starch  paste  and  a  small  crystal  of  potassium  iodide.  Acid- 
ify the  solution  with  dilute  sulphuric  acid.  Note  the  blue 
color,  due  to  free  iodine. 

Experiment  12.  Precipitation  of  elementary  osmium. 
(a)  To  a  solution  of  the  tetroxide  add  stannous  chloride. 

(b)  Try  the  action  of  zinc  and  hydrochloric  acid  upon 
a  solution  of  the  tetroxide. 

Experiment  13.  Odor  test  for  osmium.  Warm  a  dilute 
solution  of  osmium  tetroxide,  or  warm  with  nitric  acid  a 
solution  of  any  osmium  salt  of  the  lower  condition  of 
oxidation.  Note  the  odor. 

Experiment  14.  Precipitation  of  iridium  sulphide, 
(Ir2S3).  Pass  hydrogen  sulphide  through  a  solution  of 
iridium  tetrachloride.  Try  the  action  of  ammonium  sul- 
phide upon  the  precipitate. 

Experiment  15.  Formation  of  the  double  chlorides  of 
iridium  with  ammonium  and  potassium,  ((NH4)2IrCl6  and 
K2IrCl6).  To  separate  portions  of  a  fairly  concentrated 
solution  of  iridium  tetrachloride  add  ammonium  chloride 
and  potassium  chloride  respectively. 

Experiment  16.  Action  of  sodium  hydroxide  upon  iridium 
tetrachloride.  To  a  solution  of  iridium  tetrachloride  add 
some  sodium  hydroxide  in  solution.  Note  the  changes  in 
color,  dark  red  to  green  (IrCl3) . 


EXPERIMENTAL   WORK  ON  THE  PLATINUM  METALS.        181 

2lrCl4+2NaOH«2lrCl3+NaCl+H20+NaOCl. 

Warm  the  solution  and  note  the  change  to  azure  blue. 

Experiment  17.  Reduction  of  iridium  salts,  (a)  To  a 
solution  of  iridium  tetrachloride  add  oxalic  acid. 

(b)  Try  similarly  the  action  of  zinc  upon  an  acid  solu- 
tion of  the  salt. 

Experiment  18.  Action  of  sodium  hydroxide  upon 
iridium  tetrachloride.  Add  sodium  hydroxide  in  excess 
to  iridium  tetrachloride  and  warm.  Note  the  change  in 
color.  The  iridium  salt  is  said  to  be  reduced  to  the  tri- 
chloride by  this  treatment.  Acidify  with  hydrochloric 
acid  and  add  potassium  chloride.  Note  the  absence  of 
precipitation. 

Experiment  19.  Precipitation  of  rhodium  sulphide, 
(Rh2S3).  Pass  hydrogen  sulphide  through  a  solution  of 
sodium-rhodium  chloride.  Try  the  action  of  ammonium 
sulphide  upon  the  sulphide  precipitated. 

Experiment  20.  Reduction  of  rhodium  salts.  To  an 
acid  solution  of  a  rhodium  salt  add  zinc. 

Experiment  2 1 .  Formation  of  the  double  nitrite  of  potas- 
sium and  rhodium,  (K3Rh(NO2)6).  To  a  solution  of  sodium- 
rhodium  chloride  add  potassium  nitrite  in  solution  and 
warm.  Try  the  action  of  hydrochloric  acid  upon  the 
precipitate. 

Experiment  22.  Precipitation  of  rhodium  hydroxide, 
(Rh(OH)3).  Note  the  first  action  and  the  action  in  excess 
of  sodium  or  potassium  hydroxide  upon  a  solution  of  sodium- 
rhodium  chloride.  Boil  the  solution  just  obtained. 

Experiment  23.  Precipitation  of  ruthenium  sulphide, 
(Ru2S3).  (a)  To  a  solution  of  ruthenium  trichloride  add 
hydrogen  sulphide. 

(6)   Use  ammonium  sulphide  as  the  precipitant. 

Experiment  24.  Formation  of  the  soluble  double  nitrite 
of  ruthenium  and  potassium,  (K3Ru(N02)6).  To  a  solution 


1 82  THE  RARER  ELEMENTS. 

of  ruthenium  trichloride  add  a  solution  of  potassium  nitrite. 
Note  the  color.  Add  ammonium  sulphide  to  the  solution. 

Experiment  25.  Precipitation  of  ruthenium  hydroxide, 
(Ru(OH)3).  To  a  solution  of  ruthenium  trichloride  add 
sodium  or  potasshim  hydroxide  in  solution. 

Experiment  26.  Precipitation  of  metallic  ruthenium. 
To  an  acid  solution  of  a  ruthenium  salt  add  metallic  zinc. 

GOLD,  Au,  197.2. 

Discovery.  Gold  is  probably  one  of  the  earliest  known 
of  the  metals.  In  very  ancient  records  frequent  mention 
is  made  of  its  uses.  As  far  back  as  3600  B.C.  in  the  Egyp- 
tian code  of  Menes  a  ratio  of  value  between  gold  and  silver 
(2.5:1)  is  mentioned.  Rock  carvings  of  Upper  Egypt 
dating  from  2500  B.C.  show  crude  representations  of  the 
washing  of  gold-bearing  sands  in  stone  basins,  and  of  the 
melting  of  the  metal  in  simple  furnaces  by  means  of  mouth 
blowpipes.  In  fact  the  discovery  of  gold  dates  back  to 
the  beginnings  of  civilization. '  The  search  for  it  furnished 
the  motive  of  many  voyages  of  discovery  and  conquest, 
which  resulted  in  the  extension  of  civilization;  and  from 
the  desire  to  change  the  base  metals  into  gold  sprang  the 
study  of  alchemy,  from  which  developed  the  science  of 
chemistry. 

Occurrence.  Gold  occurs  in  nature  both  free  and  in 
combination.  Free  or  native  gold  is  found  (i)  as  vein 
gold,  in  the  quartz  veins  which  intersect  metamorphic 
rocks,  and  (2)  as  placer  gold,  generally  in  the  form  of  grains 
or  nuggets,  in  alluvial  deposits  of  streams.  Native  gold  is 
usually  alloyed  with  silver,  which  sometimes  amounts  to  as 
much  as  fifteen  per  cent,  of  the  alloy.  Iron  and  copper 
are  sometimes  present,  and  bismuth,  palladium,  and  rho- 
dium alloys  are  known. 


GOLD.  l»3 

In  combination  gold  is  found  as  follows: 

Petzite,  (AgAu)2Te,                      contains 18-24%  Au 

Sylvanite,  <AuAg)Te2,  "  26-29%  " 

Goldschmidtite,  Au2AgTe6,  "  31-32%  " 

Krennerite,  (Au,Ag)Te2-AuTe2,        "  30-34%  " 

Calaverite,  (Au,Ag  Te2-AuTe2,  "  38-42%  " 

Kalgoorlite,  HgAu2Ag6Te6,  "  20-21%  " 

Nagyagite,  Au2Pb14Sb8Te7S17,  "  5-12%  " 

Extraction.  The  six  processes  indicated  below  follow 
the  principal  methods  that  have  been  employed  for  the 
extraction  of  gold. 

(1)  Washing  or  Hydraulicking.     This  method  is  applied 
mainly    to    placer    deposits.     Powerful    jets    of  water  are 
directed   upon  the  gold-bearing  sands,    causing   them   to 
pass  through  a  series  of  sluices.     Because  of  its  higher 
specific  gravity  the  gold  is  largely  left  behind,  while  the 
other  materials  are  carried  away. 

(2)  Amalgamation    (primitive).     In     this     process    the 
crushed  ore  or  the  gold-bearing  sand  is  first  washed,  to 
remove  the  greater  part  of  the  light,  worthless  material, 
and  the  remainder  is  rubbed  with  mercury  in  a  mortar. 
The   amalgam   thus   obtained   is   heated,    whereupon   the 
mercury  is  volatilized  and  the  gold  remains. 

(3)  Stamp  battery  amalgamation.     The  ore  is  pulverized 
and  mixed  with  water,  and  in  the  form  of  pulp  caused  to 
pass  over  a  series  of  amalgamated  copper  plates.     Gold 
amalgam  forms  on  the  plates,  and  from  time  to  time  it  is 
removed  and  cupelled. 

(4)  Chlorination.     (a)  Vat    process.     The   crushed   ore 
is  placed  loosely  in  large  vats  and  moistened  with  water. 
Chlorine  is  forced  in,  and  the  whole  is  allowed  to  stand  for 
about  twenty -four  hours.     The  material  is  then  leached 
with  water  until  the  washings  give  no  further  test  for  gold. 
The  solution  of  gold  chloride  thus  obtained  is  treated  with 


184  THE  R4RER    ELEMENTS. 

sulphur  dioxide,  to  destroy  the  excess  of  chlorine,  and  then 
with  hydrogen  sulphide.  The  gold  sulphide  thus  precipi- 
tated is  decomposed  with  borax  and  the  gold  is  melted 
into  bullion. 

(6)  Barrel  process.  Into  large  barrels  are  put  water 
and  sulphuric  acid,  the  ore,  and  chloride  of  lime.  The 
barrels  are  then  closed  and  rotated  for  a  period  varying  from 
one  hour  to  four  hours.  At  the  end  of  that  time  the  con- 
tents are  leached  and  the  gold  is  extracted  as  described 
above. 

The  chlorination  process  is  generally  applied  to  low- 
grade  ores,  and  these  must  have  been  roasted  unless  the 
gold  occurs  in  them  native. 

(5)  Cyanide  process.  The  ore,  ground  fine,  is  placed 
in  large  vats,  and  a  dilute  solution  (.2-.  5%)  of  potassium 
cyanide  is  forced  in.  After  a  time  the  solution  is  drawn  off 
and  passed  over  zinc  shavings,  upon  which  the  gold  is  de- 
posited as  a  black  slime.  The  mixture  of  zinc  and  gold 
is  either  treated  with  sulphuric  acid,  to  dissolve  the  zinc,  or 
roasted  with  a  flux  of  niter  and  carbonate  of  soda.  The 
reactions  which  take  place  in  the  cyanide  process  may  be 
represented  as  follows: 

(i) 
(2) 


(6)  Smelting.  In  smelting  the  gold  ore  is  mixed  with 
some  other  metallic  ore  appropriately  chosen,  and  the 
mixture  is  subjected  to  intense  heat.  The  gold  alloys 
with  the  other  metal,  and  the  alloy  is  separated  from  the 
residue,  or  slag,  and  worked  for  gold.  Three  modifications 
of  this  important  process  are  in  common  use,  viz.,  lead, 
copper  matte,  and  iron  matte  smelting.  The  process  of 
lead-smelting  is  in  outline  as  follows:  The  alloy  obtained 
by  heating  a  mixture  of  gold  and  lead  ores  is  melted  with 


GOLD.  185 

zinc.  The  gold  and  silver  combine  with  the  zinc  and  rise 
to  the  surface,  leaving  the  lead  below.  The  alloy  of  gold, 
silver,  and  zinc  is  then  skimmed  off  and  roasted.  The  zinc 
passes  off,  leaving  the  gold  and  silver,  which  are  separated 
by  electrolysis. 

The  Element.  A.  Preparation.  As  extracted  from  its 
ores  gold  is  in  the  elementary  condition  (vid.  Extraction). 

B.  Properties.  Of  a  characteristic  yellow  color,  gold 
is  the  most  malleable  and  ductile  of  the  metals.  It  is  about 
as  soft  as  silver.  It  is  insoluble  in  the  common  acids,  but 
is  attacked  by  aqua  regia,  chlorine,  bromine,  and  by  potas- 
sium cyanide  in  the  presence  of  oxygen.  It  is  dissolved 
in  many  reactions  where  oxygen  is  set  free,  e.g.  by  selenic 
acid,  and  by  phosphoric  or  sulphuric  acid  in  the  presence 
of  telluric  acid,  nitric  acid,  lead  or  manganese  dioxide, 
chromium  trioxide,  or  potassium  permanganate.  It  is 
not  attacked  when  suspended  in  sulphuric  acid  and  treated 
with  oxygen  gas  (Lenher,  Jour.  Amer.  Chem.  Soc.  xxvi, 
550).  It  is  somewhat  soluble  in  hydrochloric  acid  in  the 
presence  of  light  and  manganous  chloride  (Berthelot, 
Compt.  rend,  cxxxvm,  1297),  and  in  thiocarbamide  in 
the  presence  of  oxidizing  agents  (Moir,  Proc.  Chem.  Soc. 
xxn,  105,  165).  It  has  also  been  found  to  be  slightly 
attacked  by  alkali  sulphides  and  thiosulphates.  Moissan 
has  distilled  it  in  the  electric  furnace;  he  finds  that  when 
alloys  of  copper  or  tin  with  gold  are  subjected  to  distilla- 
tion, the  copper  and  tin  distil  first  (Compt.  rend.  CXLI, 
8$3>  977).  Its  melting-point  is  1037°  C., — just  above  that 
of  copper.  Gold  alloys  with  nearly  all  the  metals.  It  is 
occasionally  found  crystallized  in  the  cubic  system.  It  is 
a  good  conductor  of  heat  and  electricity.  Its  specific 
gravity  is  19.49. 

Compounds.  A.  Typical  forms.  The  following  com- 
pounds of  gold  may  be  considered  typical  forms : 


i86 


THE  RARER  ELEMENTS. 


Oxides Au,O  Au2O2 

Hydroxide 

Aurates 

Chlorides AuCl  Au2Cl4 

Double     chlorides, 
many  of  the  types 


Bromides AuBr  Au2Br4 

Double    bromides, 

of  the  type 

Iodides Aul 

Double  iodides,  of 

the  type 

Sulphides Au^  Au2S2 

Double  sulphides. .  Au2S-Na2S 

Sulphites  (double)  Au2SO3-3Na2SO3+3H2O 

Sulphates AuSO4 

Nitrate 

Cyanides AuCN 

Double  cyanides.  .  AuCN  •  KCN 
Sulphocyanides.  .  .AuCNS-KCNS 


Au2O3 
Au(OH), 
Na2O2-Au2O2* 
BaO2-Au,O,.  etc. 
AuCl3 

AuCVRCl 

AuCl3-RCl2 
AuBr3 


AuI3 

AuI3-RI 

Au2S3 

2Au2S3-5Ag2S 

2Au2S3-3MoS2 

Au2S3-3MoS4 

Au2(S03)3-5K2S03+5H20 

Au2(SO4)rK2SO4 

Au(N05)3-HN03 

Au(CN)3 

Au(CN)3-KCN,  etc. 

Au(CNS)3-KCNS 


B.  Characteristics.  The  compounds  of  gold  are  known 
chiefly  in  two  conditions  of  oxidation,  of  which  aurous 
oxide,  (Au2O),  and  auric  oxide,  (Au2O3),  serve  as  types. 
When  metallic  gold  is  dissolved  in  aqua  regia  auric 
chloride  is  formed,  a  yellow  crystalline  salt  soluble  in 
water;  when  auric  chloride  is  heated  to  180°  C.  it  goes 
over  to  aurous  chloride,  a  white  powder  insoluble  in 
water.  The  aurous  salts  resemble  the  salts  of  silver 
and  of  copper  in  the  cuprous  condition;  the  auric  salts 
resemble  those  of  aluminum  and  of  iron  in  the  ferric 
condition.  The  auric  hydroxide,  (Au(OH)3),  is  acidic 

in  character  and  unites  with  bases  to  form  aurates  of  the 

i 
type   RAuO2.     Hydrogen  sulphide  precipitates  brownish- 


*  See  Meyer,  Compt.  rend.  CXLV,  805. 


GOLD.  187 

black  auric  sulphide,  (Au2S3  or  Au2S2  +  S),  from  cold  solu- 
tions of  gold  salts,  and  steel-gray  aurous  sulphide,  (Au2S  or 
Au2S  +  S),  from  hot  solutions.  Salts  of  gold  in  solution 
are  easily  reduced  to  the  metal  by  reducing  agents. 

Estimation.*  A.  Gravimetric.  Gold  is  weighed  as  the 
metal.  From  solutions  it  is  precipitated  by  reducing  agents, 
such  as  ferrous  sulphate,  oxalic  acid,  formaldehyde,  and 
hydrogen  dioxide  in  alkaline  solution. 

B.  Volumetric.  Gold  may  be  determined  volumetrically 
(i)  by  allowing  potassium  iodide  to  act  upon  auric  chloride, 
(AuCl3  +  3KI  =.3KCl  +  AuI  +  I2),  and  estimating  the  iodine 
thus  freed  by  means  of  thiosulphate  (Peterson,  Zeitsch. 
anorg.  Chem.  xix,  63 ;  Gooch  and  Morley,  Amer.  Jour. 
Sci.  [4]  vin,  261;  Maxson,  Amer.  Jour.  Sci.  [4]  xvi,  155);  (2) 
by  -warming  a  solution  of  auric  chloride  with  a  measured 
amount  of  arsenious  acid  solution  which  must  be  in  ex- 
cess, (3As2O3  +  4AuCl3  +  6H2O=3As2O5+i2HCl  +  4Au),  and 
determining  the  excess  of  arsenious  acid  by  iodine  in 
the  usual  way  (Rupp,  Ber.  Dtsch.  chem.  Ges.  xxxv,  2011; 
Maxson,  loc.  cit.). 

Separation.  Gold  and  platinum  fall  into  the  analyt- 
ical group  of  arsenic,  antimony,  and  tin.  From  these 
they  may  be  separated  by  the  following  process:  fusion 
of  the  sulphides  with  sodium  carbonate  and  niter,  and 
removal  of  the  arsenic  by  extraction  with  water ;  treatment 
of  the  insoluble  residue  with  zinc  and  hydrochloric  acid,' 
which  reduces  the  tin  and  antimony  to  the  metallic  con- 
dition; boiling  with  hydrochloric  acid,  which  dissolves  the 
tin;  then  with  nitric  and  tartaric  acids,  which  dissolves 
the  antimony,  leaving  gold  and  platinum. 

For  the  separation  of  gold  from  platinum  and  the  plat- 
inum metals  vid.  Platinum. 

*  For  the  estimation  of  gold  in  telluride  ores,  see  Hillebrand,  Bull.  253  (1905), 
U.  S.  Geological  Survey. 


l8S  THE  RARER  ELEMENTS. 

From  selenium  and  tellurium  gold  may  be  separated 
by  oxalic  acid,  which  precipitates  the  gold  (A.  A.  Noyes^ 
Jour.  Amer.  Chem.  Soc.  xxix,  137). 


EXPERIMENTAL  WORK  ON  GOLD. 

Experiment  i.  Extraction  of  gold  from  its  ores.  (a) 
Digest  for  several  hours  in  a  beaker  on  a  steam-bath  about 
100  grm.  of  finely  ground  gold  ore  with  a  dilute  solution  of 
potassium  cyanide,  adding  water  from  time  to  time  to  re- 
place the  liquid  evaporated.  Filter,  pass  the  filtrate  several 
times  through  a  funnel  containing  zinc  shavings,  until  upon 
testing  the  liquid  with  a  fresh  piece  of  zinc  no  discoloration 
of  the  metal  is  observed.  Dissolve  the  zinc  in  hydrochloric 
acid  to  remove  the  black  deposit.  Filter,  dissolve  the  resi- 
due in  aqua  regia,  remove  the  excess  of  acid  by  evaporation, 
and  test  for  gold  by  stannous  chloride,  ferrous  sulphate,  etc. 

(6)  Mix  in  a  glass-stoppered  bottle  about  100  grm.  of 
finely  ground  ' '  oxidized ' '  or  previously  roasted  ore  with  a 
little  bleaching  salt  and  enough  water  to  give  the  mass  the 
consistency  of  thin  paste.  Then  add  gradually  enough 
sulphuric  acid  to  start  an  evolution  of  chlorine.  Close  the 
bottle  and  shake  it,  to  insure  a  thorough  mixing  of  the 
contents.  Allow  the  action  to  go  on  for  several  hours, 
agitating  the  mass  occasionally,  and  taking  care  to  have  an 
excess  of  chlorine  present  throughout  the  process  Extract 
with  water,  concentrate  if  necessary,  and  test  for  gold  in 
the  solution.  A  two  per  cent,  solution  of  bromine  may  be 
substituted  for  the  materials  generating  chlorine. 

Experiment  2.  Precipitation  of  ike  sulphide  of  gold, 
(Au2Ss  or  Au2S2  +  S  ?) .  Into  a  cold  solution  of  auric  chloride 
pass  hydrogen  sulphide.  Try  the  action  of  yellow  am- 
monium sulphide  upon  the  precipitate. 

Experiment  3.     Formation  of  aurous  iodide,  (Aul).     To 


EXPERIMENTAL   WORK  ON  GOLD.  189 

a  solution  of  auric  chloride  add  a  few  drops  of  a  dilute 
solution  of  potassium  iodide.  Note  the  precipitate,  and 
the  solvent  action  of  an  excess  of  the  reagent. 

Experiment  4.  Formation  of  ammonia  aurate,  "ful- 
minating gold"  ((NH3)2Au2O3).  To  a  very  dilute  solution 
of  a  salt  of  gold  add  a  little  ammonium  hydroxide. 

CAUTION.  Do  not  attempt  to  isolate  the  precipitate. 
Note  that  neither  potassium  nor  sodium  hydroxide  gives 
a  precipitate  under  similar  conditions  of  dilution. 

Experiment  5.  Formation  of  the  "purple  of  Cassius" 
To  a  very  dilute  solution  of  a  gold  salt  add  a  drop  or  two 
of  dilute  stannous  chloride  solution. 

Experiment  6.  Precipitation  of  gold.  To  separate  por- 
tions of  a  solution  of  a  gold  salt  add  ferrous  sulphate  and 
oxalic  acid  in  solution.  Observe  the  color  by  transmitted 
light. 

Experiment  7.  Solvent  action  of  certain  reagents  upon 
gold.  Try  separately  upon  metallic  gold  the  action  of 
aqua  regia,  chlorine  or  bromine  water,  and  a  dilute  solution 
of  potassium  cyanide. 


CHAPTER  XI. 
THE  RARE   GASES  OF  THE  ATMOSPHERE. 

Argon,  A,  39.9  Krypton,  Kr,  81.8 

Helium,  He,  4  Neon,  Ne,  20 

Xenon,  X,   128 

Discovery.  In  1892  Lord  Rayleigh,  while  engaged  in 
the  study  of  the  density  of  elementary  gases,  made  the  im- 
portant observation  that  the  nitrogen  obtained  from  nitric 
acid  or  ammonia  was  about  one  half  of  one  per  cent,  lighter 
than  atmospheric  nitrogen  (Proc.  Royal  Soc.  LV,  340). 
An  investigation  of  this  difference  led  to  the  discovery 
two  years  later  of  the  gas  Argon  (dpyos,  -inert)  by  Lord 
Rayleigh  and  Professor  William  Ramsay  (Proc.  Royal 
Soc.  LVII,  265;  Amer.  Chem.  Jour,  xvn,  225).  An  experi- 
ment made  by  Cavendish  in  1785  seems  also  to  have  resulted 
in  the  separation  of  this  gas  (Phil.  Trans.  Roy.  Soc.  (1785) 
LXXV,  372,  and  (1788)  LXXVIII,  271). 

In  the  course  of  analytical  work  on  uraninite  undertaken 
by  Hillebrand  in  1888,  a  gas  which  he  thought  to  be  nitro- 
gen was  obtained  upon  the  boiling  of  the  mineral  with  dilute 
sulphuric  acid  (Bull.  U.  S.  Geol.  Sur.  No.  78,  p.  43 ;  Amer. 
Jour.  Sci.  [3]  XL,  384).  In  1895  Ramsay,  whose  attention 
had  been  called  to  Hillebrand 's  work,  and  who  doubted 

whether  nitrogen  could  be  obtained  by  the  method  de- 

190 


THE  RARE   GASES   OF   THE  ATMOSPHERE.  191 

scribed,  prepared  some  of  the  gas  by  Hillebrand's  process 
from  cleveite,  a  variety  of  uraninite.  He  then  sparked  the 
gas  with  oxygen  over  soda  to  remove  the  nitrogen.  Ob- 
serving very  little  contraction,  he  removed  the  excess  of 
oxygen  by  absorption  with  potassium  pyrogallate  and 
examined  the  residual  gas  spectroscopically.  The  spec- 
trum showed  argon  and  hydrogen  lines,  and  in  addition  a 
brilliant  yellow  line,  (D3),  coincident  with  the  helium  line 
of  the  solar  chromosphere  discovered  by  Lockyer  in  1868 
(Proc.  Royal  Soc.  LVIII,  65,  81).  The  only  previous  note 
regarding  helium  as  a  terrestrial  element  is  a  statement 
by  Palmieri,  in  1881,  that  a  substance  ejected  from  Vesu- 
vius showed  the  line  D3  (Rend.  Ace.  di  Napoli  xx,  233) ; 
he  failed  to  describe  his  treatment  of  the  material,  how- 
ever, and  he  seems  to  have  made  no  further  investigation  of 
the  subject.  Kayser  first  detected  helium  in  the  atmos- 
phere, in  1895  (Chem.  News  LXXII,  89),  several  months 
after  Ramsay's  discovery. 

The  year  1898  witnessed  the  discovery  by  Ramsay  and 
Travers  of  three  other  inert  atmospheric  gases.  Having 
allowed  all  but  one  seventy -fifth  of  a  given  amount  of 
liquid  air  to  evaporate,  and  having  removed  the  oxygen 
and  nitrogen  remaining  by  sparking  over  soda,  they  ob- 
tained a  small  amount  of  a  gas  which,  while  showing  a  feeble 
spectrum  of  argon,  gave  new  lines  as  well.  This  newly 
discovered  gas  they  named  Krypton,  from  Kpvnros,  hid- 
den  (Proc.  Royal  Soc.  LXIII,  405). 

By  fractioning  the  residue  after  the  evaporation  of  a 
large  amount  of  liquid  air  they  found  evidence  of  a  gas  of 
greater  density  than  krypton,  and  for  this  heavy  gaseous 
element  the  name  Xenon  (gevos,  stranger)  was  chosen 
(Chem.  News  LXXVIII,  154). 

The  third  discovery  of  the  year  by  the  same  investigators 
was  that  of  Neon  (veo?,  new),  a  gas  of  less  density  than 
argon.  The  first  fraction  obtained  from  the  evaporation 


192  THE   RARER   ELEMENTS. 

of  liquid  air  was  mixed  with  oxygen  and  sparked  over 
soda,  and  the  excess  of  oxygen  was  removed  by  phosphorus. 
The  remaining  gas  yielded  a  new  and  characteristic  spectrum 
(Proc.  Royal  Soc.  LXIII,  437). 

Occurrence.*  Argon  forms  about  one  per  cent,  of  the 
air  by  volume.  It  is  found  in  small  quantities  in  gases 
from  certain  mineral  springs,  e.g.  Bath,  Cauterets,  Wild- 
bad,  Voslau,  the  sulphur  spring  of  Harrogate;  in  the  gases 
occluded  in  rock  salt,  and  in  some  volcanic  gases  (Moissan, 
Compt.  rend,  cxxxvni,  936;  cxxxv,  1085).  It  has  been 
detected  in  some  helium-bearing  minerals,  e.g.  cleveite, 
broggerite,  uraninite,  and  malacon. 

Helium,  the  existence  of  which  was  first  observed  in 
the  sun,  occurs  in  very  small  proportion  in  the  terrestrial 
atmosphere.  The  chief  sources  of  the  gas  have  been  certain 
rare  minerals,  among  which  are  uraninite  (pitch-blende)  r 
cleveite,  monazite,  fergusonite,  samarskite,  columbite,  and 
malacon.  It  has  been  found  also  in  some  mineral  springs, 
e.g.  Bath,  Cauterets,  and  Adano,  near  Padua. 

The  other  gases  of  this  group  are  present  in  the  air  in 
very  minute  quantities.  Neon  is  said  to  constitute  0.002  5  % 
and  krypton  0.00002%  of  the  atmosphere.  Traces  of  neon 
have  been  detected  in  the  helium  from  the  springs  of  Bath. 

Extraction.  Argon,  contaminated  with  a  greater  or  less 
percentage  of  the  associated  gases,  may  be  extracted  by  the 
following  methods : 

(i)  From  atmospheric  nitrogen.  The  nitrogen  is  passed 
over  red-hot  magnesium  filings ;  a  nitride  is  thus  formed, 
while  the  argon  is  left  uncombined  (Ramsay).  Heated 
lithium  may  be  substituted  for  magnesium. 

*  See  also  Ramsay,  Chem.  News  LXXXVII,  159;  Nasini/Chem.  Zentr.  (1904) 
II,  77;  Pesendorfer,  Chem.  Ztg.  xxix,  359;  Rutherford,  Chem.  Zentr.  (1905) 
I,  848;  Kohlschutler,  Ber.  Dtsch.  chem.  Ges.  xxxvin,  1419;  Prytz,  Chem.  Zentr. 
(1905)  n,  1570;  Ewers,  Chem.  Zentr.  (1906)  i,  1319;  Moureu,  Compt.  rend. 
CXLH,  1155;  CXLIII,  795;  Kitchin,  Jour.  Chem.  Soc.  LXXXIX,  1568. 


THE  RARE   GASES    OF  THE   ATMOSPHERE.  193 

(2)  From  air.  Induction  sparks  are  passed  through  a 
mixture  of  oxygen  and  air  contained  in  a  vessel  which  is 
inverted  over  caustic  potash.  The  oxygen  and  nitrogen 
combine  and  dissolve  in  the  potassium  hydroxide,  leaving 
the  argon  (Rayleigh). 

Helium  may  be  obtained  from  its  mineral  sources  by 
boiling  the  material  with  dilute  sulphuric  acid,  or  by  heat- 
ing in  vacuo. 

Krypton  and  xenon  are  extracted  as  follows:  After 
the  evaporation  of  a  large  amount  of  liquid  air  the  residue 
is  freed  from  oxygen  and  nitrogen  and  liquefied  by  the 
immersion  of  the  containing  vessel  in  liquid  air.  The 
greater  part  of  the  argon  can  be  removed  as  soon  as  the 
temperature  rises.  By  repetitions  of  this  process  the 
three  gases  can  be  separated  from  one  another,  krypton 
exercising  much  greater  vapor  pressure  than  xenon  at  the 
temperature  of  boiling  air  (Ramsay  and  Travers,  Proc. 
Royal  Soc.  LXVII,  330). 

Neon  is  obtained  from  the  gas,  largely  nitrogen,  that 
first  evaporates  from  liquid  air.  This  gas  is  liquefied,  and 
a  current  of  air  is  blown  through  it.  The  material  that 
first  evaporates  is  passed  over  red-hot  copper,  to  remove 
the  oxygen,  and  after  being  freed  from  nitrogen  in  the 
usual  manner,  is  liquefied.  By  fractional  distillation  helium 
and  neon  are  removed,  and  argon  is  left  behind.  By  the 
use  of  liquefied  hydrogen  helium  and  neon  are  separated, 
as  neon  is  liquefied  or  solidified  at  the  temperature  of  boil- 
ing hydrogen,  while  helium  remains  gaseous.  Several 
fractionations  are  necessary  to  obtain  pure  neon  (Ramsay 
and  Travers,  Proc.  Royal  Soc.  LXVII,  330). 

Properties.  The  newly  discovered  constituents  of  the 
atmosphere  are  inert,  colorless,  probably  mohatomic  gases, 
which  have  not  been  known  to  form  definite  compounds. 

Argon  is  somewhat  soluble  *  in  water.     Its  density  is 

*  100  volumes  of  water  will  dissolve  3.7  volumes  of  argon  at  20°  C. 


194  THE  RARER.   ELEMENTS. 

19.96  and  its  specific  heat  1.645.  It  solidifies  at  —  i9i°C., 
melts  at  —  189.5°  C.,  and  boils  at  —  i85°C.  Argon  gives 
two  distinct  spectra,  according  to  the  strength  of  the  t  in- 
duction current  employed  and  the  degree  of  exhaustion  in 
the  tube.  When  the  pressure  of  the  argon  is  3  mm.  the 
discharge  is  orange-red  and  the  spectrum  shows  two  par- 
ticularly prominent  red  lines.  If  the  pressure  is  further 
reduced,  and  a  Ley  den  jar  is  intercalated  in  the  circuit, 
the  discharge  becomes  steel-blue  and  the  spectrum  shows 
a  different  set  of  lines  (Crookes,  Amer.  Chem.  Jour,  xvn, 


Helium  is  slightly  soluble*  in  water.  Its  density 
is  1.98.  Its  spectrum  is  characterized  by  five  brilliant 
lines,  —  one  each  in  the  red,  yellow,  blue-green,  blue,  and 
violet.  Reference  has  already  been  made  to  the  yellow 
line  DS. 

Krypton  is  less  volatile  than  argon.  Its  density 
is  40.78.  Its  melting-point  is  given  as  —169°  C.,  and 
its  boiling-point  as  —152°  C.f  Its  spectrum  J  is  char- 
acterized by  a  bright  line  in  the  yellow  and  one  in  the 
green. 

Xenon  also  is  less  volatile  than  argon,  and  it  has  a 
much  higher  boiling-point.  Its  density  is  64.  Its  melt- 
ing-point is  said  to  be  —140°  C.,  and  its  boiling-point 
—  109°  C.f  Its  spectrum  J  is  similar  in  character  to  that 
of  argon,  though  the  position  of  the  lines  is  different. 
With  the  ordinary  discharge  the  glow  in  the  tube  is  blue 
and  the  spectrum  shows  three  red  and  about  five  brilliant 
blue  lines.  With  the  jar  and  spark-gap  the  glow  changes 
to  green  and  the  spectrum  is  characterized  by  four 
green  lines  (Ramsay  and  Travers,  Chem.  News  LXXVIII, 

155).  _ 

*  100  volumes  of  water  will  dissolve  about  1.4  volumes  of  helium  at  20°  C. 
f  Erdmann,  Chem.  Ztg.  xxxi,  1075. 
t  See  Baly,  Proc.  Royal  Soc.  LXXII,  84. 


THE  RARE  GASES  OF  THE  ATMOSPHERE.  195 

Neon  is  more  volatile  than  argon.  Its  density  is  9.96. 
Its  melting-point  is  given  as  —253°  C.;  and  its  boiling- 
point  as  —243°  C.*  Its  spectrum  f  is  characterized  by 
bright  lines  in  the  red,  orange,  and  yellow,  and  faint 
lines  in  the  blue  and  violet. 


*  Erdmann,  Chem.  Ztg.  xxxi,  1075. 
t  See  Baly,  Proc.  Royal  Soc.  LXXII,  84. 


CHAPTER   XII. 

SOME  TECHNICAL  APPLICATIONS  OF  THE  RARER 

ELEMENTS. 

Lithium  has   found   some   use   in   the  preparation  of 
artificial  mineral  waters  and  in  medicine. 

The  chlorides  of  the  rare  earths  have  been  subjected  to 
electrolysis  (Muthmann  and  Weiss,  Liebig  Ann.  cccxxxi,  i ; 
cccxxxvn,  370),  and  have  yielded  a  so-called  "mischmetal" 
(45%  Ce,  35%  La,  Pr,  Nd,  and  20%  Sm,  Er,  Gd,  Y),  with 
which,  as  with  aluminum  in  the  Goldschmidt  process,  it 
has  been  found  possible  to  reduce  a  number  of  the  oxides 
(e.g.  MoO3,  V205,  Nb2O5,  and  Ta205)  to  the  elementary 
condition.  The  oxides  of  cerium,  neodymium,  praseo- 
dymium, and  erbium  seem  to  premise  some  application  in 
the  coloring  of  porcelain  and  glass  (Waegner,  Chem.  Ind. 
(1904)  xxvn,  No.  12).  Cerium  salts  have  been  used,  like 
aluminum  salts,  as  mordants  in  dyeing,  and  Barbieri  (Atti 
R.  Accad.  Lincei,  Roma  [5]  xvi  [i],  395)  has  described 
their  uses  as  catalyzing  agents,  their  behavior  being  similar 
to  that  of  manganese  compounds.  Ceric  sulphate  has  been 
used  in  photography  to  reduce  the  density  of  negatives 
(Lumiere  freres  and  Seywetz,  Chem.  Ztg.  Repert.  (1900), 
80),  and  both  eerie  nitrate  and  eerie  sulphate  have  been 
used  in  making  photographic  paper  (Lumiere,  Compt.  rend. 
(1893)  cxvi,  574;  Chem.  Ztg.  Repert.  (1892),  180,  235). 
Cerium  oxalate,  cerium  hypophosphate,  and  cerium-ammo- 
nium citrate  have  found  uses  in  medicine  for  sea-sickness 

196 


SOME   TECHNICAL   APPLICATIONS.  197 

and  nervous  disorders.  The  nitrates  and  salicylates  of  the 
rare  earth  elements  are  used  as  antiseptic  agents  (Merck's 
Ber.  (1897),  39;  Kopp,  Therap.  Monatshefte  (1901),  Feb. 
No.  2) .  For  purposes  of  oxidation  eerie  sulphate  has  been 
found  to  be  a  fair  substitute  for  well-known  oxidizing  agents, 
such  as  potassium  permanganate  (Zeitsch.  f.  Electrochem. 
ix,  534;  Chem.  Ztg.  xxix,  669). 

The  use  of  thorium  nitrate  in  the  manufacture  of  mantles 
for  incandescent  gas  lights  is  a  well-known  application  of 
thorium,  and  the  development  of  this  growing  and  import- 
ant industry  has  been  largely  responsible  for  the  advances 
in  rare-earth  chemistry.  The  mantles  contain  about  99% 
of  thoria  and  about  i%  of  ceria. 

Zirconium  has  found  application  in  the  manufacture  of 
the  Nernst  glowers,  about  85%  of  zirconium  oxide  to  15% 
yttrium  earth  oxides  of  the  higher  atomic  weights  being 
used  in  their  manufacture.  The  carbide  of  zirconium  is 
said  to  be  an  excellent  conductor  of  electricity ;  ninety  parts 
of  it  mixed  with  ten  parts  of  the  metal  ruthenium  have  been 
made  into  filaments  for  use  in  the  zirconium  lamp  (Sander. 
Jour.  f.  Gasbel.  XLVIII,  203,  or  Chem.  Zentr.  (1905)  i,  12^0; 
Bohm,  Chem.  Ztg.  xxxi,  985,  1014,  1037,  1049). 

Thallium  has  been  used  in  the  manufacture  of  optical 
glass,  and  is  said  to  give  a  higher  refractive  power  than 
lead  (Lenher,  Electrochem.  Ind.  (1904),  n,  61). 

For  titanium  a  number  of  applications  in  the  arts  have 
been  found.  As  ferro-titanium,  an  alloy  containing  from 
30%  to  55%  of  titanium,  it  is  used  in  the  manufacture  of 
steels ;  it  is  said  to  add  greatly  to  their  tensile  strength  and 
elastic  limit.  The  metal  is  also  being  used  to  a  certain 
extent  as  a  filament  for  incandescent  electric  lamps,  and 
has  the  advantage  over  tungsten  of  a  higher  melting-point 
and  a  higher  electrical  resistance.  Rutile,  titaniferous 
magnetite,  and  titanium  carbide  are  all  finding  some  use  as 
electrodes  with  carbon  blocks  in  arc  lamps.  Other  com- 


198  THE  RARER   ELEMENTS. 

mercial  uses  of  titanium  are  found  in  the  employment  of 
rutile  for  giving  a  yellow  color  to  porcelain  tile  and  to 
artificial  teeth;  of  titanium  chloride  and  titanous  sulphate 
as  mordants;  and  of  titanous-potassium  oxalate  as  a 
mordant  and  yellow  dye  in  the  treatment  of  leather 
(Mineral  Resources  U.  S.  (1906),  529). 

Vanadium  has  found  employment  in  a  photographic 
developer,  in  a  fertilizer  for  plants,  in  coloring  material  for 
glass,  and  with  anilin  in  a  black  dye.  Vanadyl  phosphate 
has  been  found  to  behave  physiologically  like  potassium 
permanganate  (Ephraim,  Das  Vanadin  und  seine  Verbin- 
dungen,  83).  Vanadic  acid  (V2O5)  is  employed  as  a  sub- 
stitute for  gold  bronze  in  making  a  waterproof  black  ink 
with  tannic  acid,  in  manufacturing  sulphuric  acid  by  the 
contact  process  (Kuster,  Chem.  Zentr.  (1905)  i,  328),  and 
as  a  catalyzer  to  accelerate  oxidation  processes,  such  as 
the  oxidation  of  sugar  to  oxalic  acid,  of  alcohol  to  aldehyde, 
and  of  stannous  to  stannic  salts  (Naumann,  J.  pr.  Chem. 
(2)  LXXV,  146).  Probably  of  more  importance  than  any  of 
the  foregoing  uses  of  vanadium  is  its  employment  in  the 
manufacture  of  steel,  which  gains  greatly  in  elasticity  and 
tensile  strength  by  the  presence  of  from  .15%  to  .35%  of 
this  element,  introduced  as  ferro- vanadium,  an  alloy  con- 
taining about  30%  of  vanadium.  (See  pamphlets  by 
J.  Kent  Smith,  Amer.  Vanadium  Co.) 

The  use  of  the  tantalum  filament  as  a  substitute  for 
carbon  is  an  interesting  step  in  the  development  of  incan- 
descent electric  lighting.  The  tantalum  lamp  produces  a 
light  of  one  candle  power  for  every  two  watts  of  electrical 
energy,  as  against  three  and  one-tenth  watts  required  by 
the  ordinary  carbon  filament.  The  hardness  of  this  metal 
and  its  resistance  to  chemical  action  have  suggested  its  use 
in  pens  (Mineral  Resources  U.  S.  (1906),  533). 

One  of  the  chief  uses  of  molybdenum  is  in  the  manu- 


SOME   TECHNICAL  APPLICATIONS.  199 

facture  of  ammonium  molybdate,  which  is  used  extensively 
in  the  analysis  of  phosphates,  and  has  found  some  use  in 
fireproofing,  in  coloring,  pottery  glazes,  and  as  a  germicide. 
Molybdic  acid  is  employed  to  some  extent  in  dyeing.  The 
metal  is  used  in  steels,  but  on  account  of  its  low  fusing- 
point  it  cannot  be  employed  in  filaments  for  incandescent 
lighting. 

Doubtless  the  most  interesting  use  of  tungsten  at  present 
is  that  of  its  metallic  filament  in  electric  lighting.  With 
its  melting-point  of  over  3000°  C.,  which  is  a  little  higher 
than  that  of  tantalum,  this  metal  makes  a  lamp  which 
gives  one  candle  power  of  light  for  every  one  and  twenty- 
five  hundred ths  watts  of  electrical  energy,  as  against  two 
watts  required  by  the  tantalum  lamp;  and  which  has  a 
life  of  one  thousand  or  more  hours,  or  about  twice  as  long 
as  that  of  the  carbon  and  tantalum  lamps.  The  chief  dis- 
advantage of  the  tungsten  lamp  is  the  extreme  fragility  of 
the  filament.  Tungsten- titanium,  tungsten- tantalum,  and 
tungsten-zirconium  lamps  have  been  recently  suggested, 
but  they  are  still  in  the  experimental  stage.  The  high 
melting-point  of  the  element  has  suggested  its  possible  use 
in  the  manufacture  of  crucibles  (Mineral  Resources  U.  S. 
(1906),  522).  Certain  salts  are  used  in  weighting  silks. 
Sodium  tungstate  is  employed  in  fireproofing  draperies,  and 
as  a  mordant  in  dyeing;  calcium  tungstate,  on  account  of 
its  fluorescence,  is  used  in  the  Roentgen  ray  apparatus ; 
lead  tungstate  has  been  substituted  for  white  lead  in  paints. 
Compounds  of  tungsten  have  been  employed  in  coloring 
glass  and  porcelain.  The  alloy  with  aluminum  is  used  in 
French  automobile  construction,  and  the  alloy  with  alum- 
inum and  copper  in  the  blades  of  propellers.  Alloyed  in 
small  percentages  with  steel,  tungsten  is  used  for  the 
following  purposes:  (a)  to  toughen  armor  plate;  (b)  to 
stiffen  car  springs;  (c)  to  increase  the  permanency  of 


aoo  THE  RARER   ELEMENTS. 

magnets;  (d)  to  increase  the  vibratory  response  in 
sounding-plates  and  wires  for  musical  instruments ;  (e)  to 
prevent  projectiles  and  high-speed  tools  from  losing 
their  temper  when  hot  (Van  Wegenen,  Chem.  Engineer, 
iv,  217). 

Uranium  salts  are  used  in  the  production  of  certain 
velvety-black  glazes  for  pottery,  and  of  greenish-yellow 
iridescent  glass.  The  possible  use  of  uranium  in  steels 
has  been  mentioned  (Lenher,  Electrochem.  Ind.  (1904), 

ii,  61). 

Elementary  selenium  has  the  peculiar  property  of  being 
a  fairly  good  conductor  of  electricity  in  the  light,  while  in 
the  dark  it  is  practically  a  non-conductor.  This  property 
has  been  made  of  service  in  the  construction  of  electrical 
apparatus  for  automatically  lighting  and  extinguishing  gas- 
buoys,  for  exploding  torpedoes  by  a  ray  of  light,  for  tele- 
phoning along  a  ray  of  light,  for  transmitting  sounds  and 
photographs  to  a  distance  by  telegraph  or  telephone  wire, 
and  for  measuring  the  quantity  of  Roentgen  rays  in  thera- 
peutic applications  (Hess,  Mineral  Resources  U.  S.  (1906), 
1271). 

The  uses  of  platinum  in  the  manufacture  of  chemical 
apparatus,  jewelry,  etc.,  are  so  familiar  as  to  need  no 
description 

Palladium,  because  of  its  hardness  and  unalterability  in 
air,  is  used  for  graduated  surfaces  of  fine  apparatus. 

Iridium,  alloyed  with  osmium,  is  employed  for  compass- 
bearings  and  for  tips  of  gold  pens.  Its  alloy  with  platinum 
is  used  in  the  manufacture  of  laboratory  apparatus  and 
for  standard  weights  and  measures.  The  oxide  finds  use  in 
china-painting. 

Osmium  has  long  been  employed  as  a  stain  in  micro- 
scopic work,  and  more  recently  as  a  filament  for  incan- 
descent lamps  (Jour.  f.  Gasbel.  XLIV,  101;  XLVIII,  184; 


SOME   TECHNICAL  APPLICATIONS.  2oi 

Chem.  Zentr.(iQoi)  i,  554;  (1905)  i,  974;  (1905)  n,  1480; 
(1907)  u,  433). 

Ruthenium,  as  has  been  already  stated,  has  been  mixed 
with  zirconium  carbide  for  use  in  the  filament  of  the  zir- 
conium lamp. 

The  uses  of  gold  in  coinage,  in  jewelry,  and  in  dentistry 
need  no  description. 


CHAPTER   XIII.  . 

THE  QUALITATIVE  SEPARATION  OF  THE  RARER 

ELEMENTS. 

The  following  schemes  of  separation,  very  briefly  out- 
lined, will  give  some  idea  of  the  problems  of  qualitative 
analysis  in  the  presence  of  some  of  the  rarer  elements. 
None  of  the  schemes  given  considers  the  possible  presence 
of  all  of  the  rarer  elements.  Tables  I  and  II  give  an  out- 
line of  the  work  of  Noyes  and  his  associates  so  far  as  it 
has  been  published.  No  attempt  has  been  made  here  to 
take  up  the  study  of  the  separation  methods  in  detail,  not 
to  indicate  the  processes  used  for  the  separation  of  the 
commoner  elements  from  each  other  when  the  rarer 
elements  are  not  involved.  All  these  processes  are  fully 
ciscussed  in  the  original  papers,  to  which  reference  is 
made. 

In  Table  III  the  method  suggested  by  Bohm  has  been 
put  into  diagrammatic  form.  In  this  scheme  no  attempt 
was  made  by  Bohm  to  give  anything  further  than  a  process 
for  the  separation  of  the  rare  earths  from  other  elements 
and  from  one  another.  To  make  the  table  more  complete, 
however,  methods  for  the  separation  of  the  other  rare 
elements  mentioned  have  been  supplied. 

202 


THE  QUALITATIVE  SEPARATION. 


203 


204 


THE  R/IRER   ELEMENTS. 


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206 


THE  RARER  ELEMENTS. 


TABLE  IV. 

The  alkalies  present  as  chlorides. 
Dehydrate  with  amyl  alcohol. 


Na,  K,  Rb,  Cs. 

Dissolve  in  a  few  drops  of  water, 

boil  with  Ag2CO3,  and  filter. 
Evaporate  to  dryness,  and  boil 

with  amyl  alcohol. 


Li.     Confirm  by  spectroscope. 


Acidify  with  HC1,  add  H2PtCl« 
and  ethyl  alcohol  to  50%  of 
the  total  volume. 


"IF 

Cs.  Confirm   (i)   by  spectroscope, 

(2)  by  precipitation  with  a  solution 
of  PbO2  in  HC1.     See  page  15. 


K,  Rb,  as  chloroplatinates.  Decompose  by  gentle  ignition 
or  H2S,  remo\e  Pt,  add  a  little  aluminum  sulphate  and 
crystallize.  RbAl(SO4)2+i2H2O  crystallizes  before 
KAlSO4+i2H2O.  See  page  12.  Confirm  by  spectro- 
scope. 


TYPICAL  ABSORPTION  SPECTRA  OF  THE  RARE  KARTTIS- 


INDEX. 


Actinium 32 

Argon 190 

Beryllium 17 

Caesium    9 

Cerium 56,  196 

Columbium 115 

Decipium 61 

Dysprosium 51 

Erbium 51,  196 

Erythronium 107 

Europium 51 

Gadolinium 54 

Gallium 82 

Germanium 104 

Glucinum .     , 17 

Gold 182,  201 

Helium 190 

Holmium 51 

Indium 85 

Ionium 28 

Iridium 170,  200 

Krypton 190 

Lanthanum 61 

Lithium   I,  196 

Lutecium 51 

Menachite 96 

Molybdenum 1 25,  198 

Monium 52 

Neodymium 61,  196 

Neon         190 

Neoytterbium _  51 


PAGE 

Niobium 115 

Ochroite 56 

Osmium. 170,  200 

Palladium 170,  200 

Platinum 161,  200 

Polonium 32 

Praseodymium 61,  196 

Radio  elements 25 

Radium 29. 

Rare  earths 35,  196,  197 

Rhodium 170 

Rubidium 6 

Ruthenium 170,  197,  201 

Samarium 61 

Scandium 61 

Selenium 144,  200 

Tantalum 115,  198 

Tellurium 152 

Terbium 54 

Thallium 88,  197 

Thorium 33,  70,  197 

Thulium 51 

Titanium 96,  197 

Tungsten 132,  199 

Uranium 27,  137,  200 

Vanadium 107,  198 

Victorium 51 

Xenon 190 

Ytterbium  , 51 

Yttrium    .  , 46 

Zirconium 75,  197 

207 


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Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  i  50 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Towne's  Locks  and  Builders'  Hardware i8mo,  mor.  3  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Contracts 8vo,  3  oo 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Wilson's  Air  Conditioning i2mo,  i  50 

Worcester  and  Atkinson's  Small  Hospitals,  Establishment  and  Maintenance, 
Suggestions  for  Hospital  Architecture,  wkh  Plans  for  a  Small  Hospital. 

I2mo,  i  25 

ARMY  AND  NAVY. 

Bernadou's  Smokeless  Powder,  Nitro-cellulose,  and  the  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

Chase's  Art  of  Pattern  Making i2mo,  2  50 

Screw  Propellers  and  Marine  Propulsion 8vo,  3  oo 

*  Cloke's  Enlisted  Specialist's  Examiner 8vo,  2  oo 

Gunner's  Examiner 8vo,  r  50 

Craig's  Azimuth 4to,  3  50 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States. 8vo,  7  po 

Sheep,  7  50 

De  Brack's  Cavalry  Outpost  Duties.     (Carr) 24010,  mor.  2  oo 

*  Dudley's  Military  Law  and  the  Procedure  of  Courts-martial . .  Large  i2mo,  2  50 
Durand's  Resistance  and  Propulsion  of  Ships. 8vo,  5  oo 

2 


*  Dyer's  Handbook  of  Light  Artiller* i2mo,  3  oo 

Eissler's  Modern  High  Explosives Svo,  4  oo 

*  Fiebeger's  Text-book  on  Field  Fortification Large  12 mo,  2  oo 

Hamilton  and  Bond's  The  Gunner's  Catechism i8mo,  i  oo 

*  Hoff ' s  Elementary  Naval  Tactics 8vo,  i  50 

Ingalls's  Handbook  of  Problems  in  Direct  Fire 8vo,  4  oo 

*  Lissak's  Ordnance  and  Gunnery 8vo.  6  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables Svo,  i  oo 

*  Lyons's  Treatise  on  Electromagnetic  Phenomena.  Vols.  I.  and  II..  Svo,  each,  6  oo 

*  Mahan's  Permanent  Fortifications.     (Mercur) Svo,  half  mor.  7  50 

Manual  for  Courts-martial i6mo,  mor.  i  50 

*  Mercur's  Attack  of  Fortified  Places i2mo,  2  oo 

*  Elements  of  the  Art  of  War Svo,  4  oo 

Metcalf's  Cost  of  Manufactures — And  the  Administration  of  Workshops.  .Svo,  5  oo 

Nixon's  Adjutants'  Manual 241110,  i  oo 

Peabody's  Naval  Architecture Svo,  7  50 

*  Phelps's  Practical  Marine  Surveying Svo,  2  50 

Putnam's  Nautical  Charts Svo,  2  oo 

Sharpe's  Art  of  Subsisting  Armies  in  War i8mo,  mor.  i  50 

*  Tupes  and  Poole's  Manual  of  Bayonet  Exercises  and    Musketry  Fencing. 

241110,  leather,  50 

*  Weaver's  Military  Explosives Svo,  3  oo 

Woodhull's  Notes  on  Military  Hygiene i6mo,  I  50 


ASSAYING. 

Betts's  Lead  Refining  by  Electrolysis Svo,  4  oo 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

i6mo,  mor.  i  50 

Furman's  Manual  of  Practical  Assaying Svo,  3  oo 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments.  .  .  .Svo,  3  oo 

Low's  Technical  Methods  of  Ore  Analysis Svo,  3  oo 

Miller's  Cyanide  Process I2mo,  i  oo 

Manual  of  Assaying I2mo,  i  oo 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.     (Waldo) i2mo,  2  50 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores Svo,  2  oo 

Ricketts  and  Miller's  Notes  on  Assaying Svo,  3  oo 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc) Svo,  4  oo 

Dike's  Modern  Electrolytic  Copper  Refining Svo,  3  oo 

Wilson's  Chlorination  Process I2mo,  i  50 

Cyanide  Processes , i2mo.  i  50 


ASTRONOMY. 

Comstock's  Field  Astronomy  for  Engineers Svo,  2  50 

Craig's  Azimuth 4to,  3  50 

Crandall's  Text-book  on  Geodesy  and  Least  Squares Svo,  3  oo 

Doolittle's  Treatise  on  Practical  Astronomy Svo,  4  oo 

Gore's  Elements  of  Geodesy Svo,  2  50 

Hayford's  Text-book  of  Geodetic  Astronomy Svo,  3  oo 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy Svo,  2  50 

*  Michie  and  Harlow's  Practical  Astronomy Svo,  3  oo 

Rust's  Ex-meridian  Altitude,  Azimuth  and  Star-Finding  Tables Svo,  5  oo 

*  White's  Elements  of  Theoretical  and  Descriptive  Astronomy i2mo,  2  oo 

3 


CHEMISTRY. 

*  Abderhalden's  Physiological  Chemistry  in  Thirty  Lectures.    (Hail  and  Defren) 

8vo,  5  oo 

*  Abegg's  Theory  of  Electrolytic  Dissociation,    (von  Ende) i2mo,  i   25 

Alexeyeff's  General  Principles  of  Organic  Syntheses.     (Matthews) 8vo,  3  oo 

Allen's  Tables  for  Iron  Analysis 8vo,  3  oo 

Arnold's  Compendium  of  Chemistry.     (Mandel) Large  i2mo,  3  50 

Association  of  State  and  National  Food  and  Dairy  Departments,  Hartford, 

Meeting,  1906 8vo,  3  oo 

Jamestown  Meeting,  1907 8vo,  3  oo 

Austen's  Notes  for  Chemical  Students 12010,  i  50 

Baskerville's  Chemical  Elements.     (In  Preparation.) 

Bernadou's  Smokeless  Powder. — Nitro-cellulose,  and  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

Bilts's  Chemical  Preparations.     (Hall  and  Blanchard).     (In  Press.) 

*  Blanchard's  Synthetic  Inorganic  Chemistry I2mo,  i  co 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  i  50 

Brush  and  Penfield's  Manual  of  Determinative  Mineralogy 8vo,  4  oo 

*  Claassen's  Beet-sugar  Manufacture.     (Hall  and  Rolfe) 8vo,  3  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.    (Boltwood). .  .8vo,  3  oo 

Cohn's  Indicators  and  Test-papers i2mo,  2  oo 

Tests  and  Reagents 8vo,  3  oo 

*  Danneel's  Electrochemistry.     (Merriam) i2mo,  i   25 

Dannerth's  Methods  of  Textile  Chemistry i2mo,  2  oo 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess) 8vo,  4  oo 

Eakle's  Mineral  Tables  for  the  Determination  of  Minerals  by  their   Physical 

Properties 8vo,  125 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott) 8vo,  3  oo 

Erdmann's  Introduction  to  Chemical  Preparations.     (Dunlap) i2mo,  i   25 

*  Fischer's  Physiology  of  Alimentation Large  i2mo,  2  oo 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

i2mo,  mor.  i  50 

Fowler's  Sewage  Works  Analyses i2mo,  2  oo 

Fresenius's  Manual  of  Qualitative  Chemical  Analysis.     (Wells) 8vo,  5  oo 

Manual  of  Qualitative  Chemical  Analysis.  Part  I.  Descriptive.   (Wells)  8vo,  3  oo 

Quantitative  Chemical  Analysis.     (Cohn)     2  vols 8vo,  12  50 

When  Sold  Separately,  Vol.  I,  $6.     Vol.  II,  88. 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Furman's  Manual  of  Practical  Assaying 8vo,  3  oo 

*  Getman's  Exercises  in  Physical  Chemistry i2mo,  2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers I2mo,  i   25 

*  Gooch  and  Browning's  Outlines  of  Qualitative   Chemical  Analysis. 

Large  i2iro,  i  25 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woll) i2mo,  2  oo 

Groth's  Introduction  to  Chenrcal  Crystallography  (Marshall) i2mo.  i  25 

Hammarsten's  Text-book  of  Physiological  Chemistry.     (Mandel) 8vo,  4  oo 

Hanausek's  Microscopy  of  Technical  Products.     (Winton) 8vo,  5  oo 

*  Haskins  and  Macleod's  Organic  Chemistry i2mo,  2  oo 

Helm's  Principles  of  Mathematical  Chemistry.     (Morgan) i2mo,  i  50 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  mor.  2  50 

*  Herrick's  Denatured  or  Industrial  Alcohol ....    8vo  4  oo 

Hinds's  Inorganic  Chemistry 8vo,  3  oo 

*  Laboratory  Manual  for  Students i2mo,  i  oo 

*  Holleman's    Laboratory   Manual    of   Organic    Chemistry  for   Beginners. 

(Walked i2mo,  i  oo 

Text-book  of  Inorganic  Chemistry.     (Cooper) 8vo,  2  50 

Text-book  of  Organic  Chemistry.     (Walker  and  Mott) 8vo,  2  50 

4 


Eolley  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments ,  and  Varnishes. 

Large  12010,  2  50 

Hopkins's  Oil-chemists'  Handbook 8vo,  3  oo 

Iddings's  Rock  Minerals 8vo,  5  oo 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo,  I  25 

Johannsen's  Determination  of  Rock-forming  Minerals  in  Thin  Sections  .  .8vo,  4  oo 
Johnson's  Chemical  Analysis  of  Special  Steel.     Steel-making.     (Alloys  and 

Graphite.) Large  12010,  3  oo 

Keep's  Cast  Iron 8vo,  2  50 

Ladd's  Manual  of  Quantitative  Chemical  Analysis I2mo,  i  oo 

JLandauer's  Spectrum  Analysis.     (Tingle) 8vo,  3  oo 

*  L,angwortny  and   Austen's   Occurrence   of   Aluminium   in  Vegetable  Prod- 

ucts, Animal  Products,  and  Natural  Waters 8vo,  2  oo 

Lassar-Cohn's  Application  of  Some  General  Reactions  to  Investigations  in 

Organic  Chemistry.  'Tingle) i2mo,  i  oo 

Leach's  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,  7  50 

Lob's  Electrochemistry  of  Organic  Compounds.  (Lorenz) 8vo,  3  oo 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments 8vo,  3  oo 

Low's  Technical  Method  of  Ore  Analysis 8vo,  3  oo 

Lunge's  Techno-chemical  Analysis.  (Cohn) I2m:>,  i  oo 

*  McKay  and  Larsen's  Principles  and  Practice  of  Butter-making 8vo,  i  50 

Maire's  Modern  Pigments  and  their  Vehicles 12010,  2  oo 

Mandel's  Handbook  for  Bio-chemical  Laboratory i2mo,  i  50 

*  Martin's  Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe .  .  12010,  60 
Mason's  Examination  of  Water.     (Chemical  and  Bacteriological. )..       12010,  i   25 

Water-supply.     (Considered  Principally  from    a    Sanitary   Standpoint. 

8vo,  4  oo 

*  Mathewson's  First  Principles  of  Chemical  Theory 8vo,  i   oo 

Matthews's  Textile  Fibres.     2d  Edition,  Rewritten 8vo,  4  oo 

*  Meyer's  Determination  of  Radicle?  in  Carbon  Compounds.     (Tingle)- .  12010,  i  25 
Miller's  Cyanide  Process 12010,  i  oo 

Manual  of  Assaying .  .  .  12010,  i  oo 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.  (Waldo) i2mo,  2  50 

Mixter's  Elementary  Text-book  of  Chemistry 12010,  i  50 

Morgan's  Elements  of  Physical  Chemistry i?,mo,  3  oo 

Outline  of  the  Theory  of  Solutions  and  its  Results 12010,  i  oo 

*  Physical  Chemistry  for  Electrical  Engineers 12010,  i   50 

Morse's  Calculations  used  in  Cane-sugar  Factories 16010.  mor.  i  50 

*  Muir's  History  of  Chemical  Theories  and  Laws 8vo,  4  oo 

Mulliken's  General  Method  for  the  Identification  of  Pure  Organic  Compounds. 

Vol.  I Large  8vo,  5  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Ostwald's  Conversations  on  Chemistry.     Part  One.     (Ramsey1) 12010,  i  50 

"                "            "              Part  Two.     (Turnbull) i2mo,  200 

*•  Palmer's  Practical  Test  Book  of  Chemistry i2mo,  i  oo 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.     (Fischerl .....  i2mo,  i   25 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  50 
Tables   of  Minerals,  Including  the   Use   of  Minerals  and  Statistics  of 

Domestic  Production gvo>  T  oo 

Pictet's  Alkaloids  and  their  Chemical  Constitution.     (Biddle). 8vo,  5  oo 

Poole's  Calorific  Power  of  Fuels 8vo,  3  oo 

Prescott  and  Winslow's  Elemeots  of  Water  Bacteriology,  with  Special  Refer- 

eoce  to  Sanitary  Water  Analysis i2mo,  i  50 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  •>$  oo 

Richards  and  Woodmao's  Air,  Water,  and  Food  from  a  Sanitary  Standpoint.. 8 vo,  2  oo 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  oo 

Rideal's  Disinfection  and  the  Preservation  of  Food 8vo,  4  oo 

Sewage  and  the  Bacterial  Purification  of  Sewage 8vo.'  4  oo 

5 


Riggs's  Elementary  Manual  for  the  Chemical  Laboratory 8vo,  i  25 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc) 8vo,  4  oo 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo.  2  oo 

Whys  in  Pharmacy ,  I2mo,  i  oo 

Ruer's  Elements  of  Metallography.     (Mathewson)     (In  Preparation.) 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Salkowski's  Physiological  and  Pathological  Chemistry.     (Orndorff) 8vo,  2  50 

Schimpf's  Essentials  of  Volumetric  Analysis I2mo,  i   25 

*  Qualitative  Chemical  Analysis 8vo,  i   25 

Text-book  of  Volumetric  Analysis I2mo,  2  50 

Smith's  Lecture  Notes  on  Chemistry  for  Dental  Students 8vo,  2  50 

Spencer's  Handbook  for  Cane  Sugar  Manufacturers i6mo,  mor.  3  oo 

Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  mor.  3  oo 

Stockbridge's  Rocks  and  Soils 8vo,  2  50 

*  Tillman's  Descriptive  General  Chemistry ,8vo,  3  oo 

*  Elementary  Lessons  in  Heat 8vo,  i   50 

Treadwell's  Qualitative  Analysis.     (Hall) 8vo,  3  oo 

Quantitative  Analysis.     (Hall) 8vo,  4  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Van  Deventer's  Physical  Chemistry  for  Beginners.     (Boltwood) i2mo,  i  50 

Venable's  Methods  and  Devices  for  Bacterial  Treatment  of  Sewage 8vo,  3  oo 

Ward  and  Whipple's  Freshwater  Biology.     (In  Press.) 

Ware's  Beet-sugar  Manufacture  and  Refining.     Vol.  I Small  8vo,  4  oo 

Vol.11 SmallSvo,  500 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8vo,  2  oo 

*  Weaver's  Military  Explosives 8vo,  3  oo 

Wells's  Laboratory  Guide  in  Qualitative  Chemical  Analysis 8vo,  i  50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students i2mo,  i  50 

Text-book  of  Chemical  Arithmetic I2mo,  i  25 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Wilson's  Chlorination  Process I2mo,  i  50 

Cyanide  Processes I2mo,  i  50 

Winton's  Microscopy  of  Vegetable  Foods .  8vo,  7  50 

CIVIL  ENGINEERING. 

BRIDGES  AND  ROOFS.     HYDRAULICS.     MATERIALS   OF    ENGINEER- 
ING.    RAILWAY   ENGINEERING. 

Baker's  Engineers'  Surveying  Instruments i2mo,  3  oo 

Bixby's  Graphical  Computing  Table Paper  19^X24!  inches.  25 

Breed  and  Hosmer's  Principles  and  Practice  of  Surveying.     2  Volumes. 

Vol.  I.     Elementary  Surveying 8vo,  3  oo 

Vol.  II.     Higher  Surveying 8vo,  2  50 

*  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  Canal 8vo,  3  50 

Comstock's  Field  Astronomy  for  Engineers 8vo,  2  50 

*  Corthell's  Allowable  Pressures  on  Deep  Foundations 12010,  i  25 

Crandall's  Text-book  on  Geodesy  and  Least  Squares 8vo,  3  oo 

Davis's  Elevation  and  Stadia  Tables 8vo,  i  oo 

Elliott's  Engineering  for  Land  Drainage I2mo,  i  50 

Practical  Farm  Drainage i2mo,  t  oo 

*Fiebeger's  Treatise  on  Civil  Engineering 8vo,  5  oo 

Flemer's  Phototopographic  Methods  and  Instruments 8vo,  5  oo 

Folwell's  Sewerage.     (Designing  and  Maintenance.) 8vo,  3  oo 

Freitag's  Architectural  Engineering 8vo,  3  So 

French  and  Ives's  Stereotomy 8vo,  2  50 

Goodhue's  Municipal  Improvements i2mo,  i  50 

Gore's  Elements  of  Geodesy 8vo»  2  SO 

*  Hauch's  and  Rice's  Tables  ot  Quantities  for  Preliminary  Estimates  . .  12010,  x  25 


Hayford's  Text-book  of  Geodetic  Astronomy 8vo,  3  oo 

Bering's  Ready  Reference  Tables.     (Conversion  Factors) i6mo,  mor.  2  50 

Howe's  Retaining  Walls  for  Earth izmo,  i   25 

*  Ives's  Adjustments  of  the  Engineer's  Transit  and  Level i6mo,  Bds.  25 

Ives  and  Hilts's  Problems  in  Surveying i6rno,  mor.  i   50 

Johnson's  (J.  B.)  Theory  and  Practice  of  Surveying Small  8vo,  4  oo 

Johnson's  (L.  J.)  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Kinnicutt,  Winslow  and  Pratt's  Purification  of  Sewage.     (In  Preparation.) 
Laplace's    Philosophical    Essay    on    Probabilities.       (Truscott    and   Emory) 

i2mo,  2  oo 

Mahan's  Descriptive  Geometry 8vo,  i  50 

Treatise  on  Civil  Engineering.  (1873.)  (Wood) 8vo,  5  oo 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

Merriman  and  Brooks's  Handbook  for  Surveyors i6mo,  mor.  2  oo 

Nugent's  Plane  Surveying 8vo,  3  50 

Ogden's  Sewer  Construction 8vo,  3  oo 

Sewer  Design I2mo5  2  oo 

Parsons's  Disposal  of  Municipal  Refuse 8vo,  2  oo 

Patton's  Treatise  on  Civil  Engineering 8vo,  half  leather,  7  50 

Reed's  Topographical  Drawing  and  Sketching  4to,  5  oo 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  4  oo 

Riemer's  Shaft-sinking  under  Difficult  Conditions.  (Corning  and  Peele). .  8vo,  3  oo 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  i  50 

Smith's  Manual  of  Topographical  Drawing.  (McMillan) 8vc,  2  50 

Soper's  Air  and  Ventilation  of  Subways Large  i2mo,  2  50 

Tracy's  Plane  Surveying i6mo,  mor.  3  oo 

*  Trautwine's  Civil  Engineer's  Pocket-book i6mo,  mor.  5  oo 

Venable's  Garbage  Crematories  in  America 8vo,  2  oo 

Methods  and  Dtvices  for  Bacterial  Treatment  of  Sewage 8vo,  3  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  co 

Sheep,  6  50 

Law  of  Contracts 8vo,  3  oo 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

*  Waterbury's  Vest-Pocket   Hand-book   of    Mathematics   for   Engineers. 

2gX 5J!  inches,  mor.  i   oo 
Webb's  Problems  in  the  Use  and  Adjustment  of  Engineering  Instruments. 

i6mo,  mor.  i  25 

Wilson's  (H.  N.)  Topographic  Surveying 8vo,  3  50 

Wilson's  (W.  L.)  Elements  of  Railroad  Track  and  Construction i2mo,  2  oo 

BRIDGES  AND  ROOFS. 

Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges.  .8vo,  2  oo 

Burr  and  Falk's  Design  and  Construction  of  Metallic  Bridges 8vo,  5  oo 

Influence  Lines  for  Bridge  and  Roof  Computations..  .  ! 8vo,  3  oo 

Du  Bois's  Mechanics  of  Engineering.     Vol.  II.  . . , Sir  all  4:0,  10  oo 

Foster's  Treatise  on  Wooden  Trestle  Bridges „ 4to,  5  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

French  and  Ives's  Stereotomy 8vo,  2  50 

Greene's  Arches  in  Wood,  Iron,  and  Stone 8vo,  2  so 

Bridge  Trusses 8vo,  2  50 

Roof  Trusses 8^0,  i  25 

Grimm's  Secondary  Stresses  in  Bridge  Trusses 8vo,  2  <-<> 

Heller's  Stresses  in  Structures  and  the  Accompanying  Deformations 8vo,  3  oo 

Howe's  Design  of  Simple  Roof- trusses  in  Wood  and  Steel 8vo,  2  oo 

Symmetrical  Masonry  Arches 8vo,  2  50 

Treatise  on  Arches 8vo,  4  oo 

7 


Johnson    Bryan,  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures.. .  < Small  4to,  10  oo 

Merrlinan  and  Jacoby's  Text-book  on  Roofs  and  Bridges : 

Part  I.      Stresses  in  Simple  Trusses 8vo,  2  50 

Part  II.    Graphic  Statics 8vo,  2  50 

Part  III.  Bridge  Design 8vo,  2  50 

Part  IV.   Higher  Structures Svo,  2  50 

Morison's  Memphis  Bridge Oblong  4to,  10  oo 

Sondericker's  Graphic  Statics,  with  Applications  to  Trusses,  Beams,  and  Arches. 

8vo,  2  oo 

Waddell's  De  Pontibus,  Pocket-book  for  Bridge  Engineers i6mo,  mor,  2  oo 

*  Specifications  for  Steel  Bridges i2mo,  50 

Waddell  and  Harrington's  Bridge  Engineering.     (In  Preparation.) 

Wright's  Designing  of  Draw-spans.     Two  parts  in  one  volume 8vo,  3  50 

HYDRAULICS. 

Barnes's  Ice  Formation 8vo,  3  oo 

Bazin's  Experiments  upon  the  Contraction  of  the  Liquid  Vein  Issuing  from 

an  Orifice.     (Trautwine) 8vo,  2  oo 

Bovey's  Treatise  on  Hydraulics 8vo,  5  oo 

Church's  Diagrams  of  Mean  Velocity  of  Water  in  Open  Channels. 

Oblong  4to,  paper,  i  50 

Hydraulic  Motors 8vo,  2  oo 

Mechanics  of  Engineering 8vo,  6  oo 

Coffin's  Graphical  Solution  of  Hydraulic  Problems i6mo,  mor.  2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power 12 mo,  3  oo 

Folwell's  Water-supply  Engineering 8vo,  4  oo 

Frizell's  Water-power 8vo,  5  oo 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Water-filtration  Works i?.mo,  2  50 

Ganguillet  and  Kutter's  General. Formula  for  the  Uniform  Flow  of  Water  in 

Rivers  and  Other  Channels.     (Hering  and  Trautwine) 8vo,  4  oo 

Hazen's  Clean  Water  and  How  to  Get  It Large  ismo,  i  50 

Filtration  of  Public  Water-supplies Svo,  3  oo 

Hazlehurst's  Towers  and  Tanks  for  Water- works Svo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

Conduits Svo,  2  oo 

Hoyt  and  Grover's  River  Discharge Svo,  2  oo 

Hubbard  and  Kiersted's  Water-works  Management  and  Maintenance 8vo,  4  «o 

*  Lyndon's  Development  and  Electrical  Distribution  of  Water  Power.  .  .  .8vo,  3  oo 
Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

Svo,  4  oo 

Merriman's  Treatise  on  Hydraulics Svo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics Svo,  4  oo 

*  Molitor's  Hydraulics  of  Rivers,  Weirs  and  Sluices Svo,  2  oo 

*  Richards's  Laboratory  Notes  on  Industrial  Water  Analysis Svo,  o  50 

Schuyler's   Reservoirs   for   Irrigation,    Water-power,    and    Domestic    Water- 
supply.     Second  Edition,  enlarged Large  Svo,  6  oo 

*  Thomas  and  Watt's  Improvement  of  Rivers   4to,  6  oo 

Turneaure  and  Russell's  Public  Water-supplies Svo,  5  oo 

Wegmann's  Design  and  Construction  of  Dams.     5th  Ed.,  enlarged 4to,  6  oo 

Water-supply  of  the  City  of  New  York  from  1658  to  1895 4to,  10  oo 

Whipple's  Value  of  Pure  Water Large  i2mo,  i  oo 

Williams  and  Hazen's  Hydraulic  Tables Svo,  i  50 

Wilson's  Irrigation  Engineering Small  Svo,  4  oo 

Wolff's  Windmill  HS  a  Prime  Mover Svo,  300 

Wood's  Elements  of  Analytical  Mechanics « Svo,  3  oo 

Turbines 8vo,  2  50 

8 


MATERIALS  OF  ENGINEERING. 


Baker's  Roads  and  Pavements 8vo,  5  oo 

Treatise  on  Masonry  Construction 8vo,  5  oo 

Birkmire's  Architectural  Iron  and  Steel 8vo,  3  50 

Compound  Riveted  Girders  as  Applied  in  Buildings 8vo,  2  oo 

Black's  United  States  Public  Works Oblong  4to,  5  oo 

Bleininger's  Manufacture  of  Hydraulic  Cement.      (In  Preparation.) 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Byrne's  Highway  Construction 8vo,  5  oo 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

i6mo,  3  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Du  Bois's  Mechanics  of  Engineering. 

Vol.    I.  Kinematics,  Statics,  Kinetics Small  4to,  7  50 

Vol.  II.  The  Stresses  in  Framed  Structures,  Strength  of  Materials  and 

Theory  of  Flexures Small  4to,  10  oo 

*Eckel's  Cements,  Limes,  and  Plasters 8vo,  6  oo 

Stone  and  Clay  Products  used  in  Engineering.     (In  Preparation.) 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Graves's  Forest  Mensuration 8vo,  4  oo 

Green's  Principles  of  American  Forestry I2mo,  i   50 

*  Greene's  Structural  Mechanics 8vo,  2  50 

Ho;ly  a.id  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments  and  Varnishes 

Large  i2mo,  2  50 
Johnson's  (C.  M.)  Chemical  Analysis  of  Special  Steels.     (In  Preparation.) 

Johnson's  (J.  B.)  Materials  of  Construction Large  8vo,  6  oo 

Keep's  Cast  Iron 8vo,  2  50 

Kidder's  Architects  and  Builders'  Pocket-book i6mo,  5  oo 

Lanza's  Applied  Mechanics 8vo,  7  50 

Maire's  Modern  Pigments  and  their  Vehicles I2mo,  2  oo 

Martens's  Handbook  on  Testing  Materials.     (Henning)     2  vols 8vo,  7  50 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Merriman's  Mechanics  of  Materials .8vo,  5  oo 

*  Strength  of  Materials i2mo,  i  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Morrison's  Highway  Engineering 8vo,  2  50 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  oo 

Rice's  Concrete  Block  Manufacture 8vo,  2  oo 

Richardson'^;  Modern  Asphalt  Pavements 8vo,  3  oo 

Richey's  Handbook  for  Superintendents  of  Construction i6mo,  mor.  4  oo 

*  Ries's  Clays:  Their  Occurrence,  Properties,  and  Uses 8vo,  5  oo 

Sabir.'s  Industrial  and  Artistic  Technology  of  Paints  ard  Varnish 8vo,  3  oo 

*Schwarz'sLong1eafP5nein  Virgin  Forest i2mo,  i   25 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Spalding's  Hydraulic  Cement I2m°.  2  ° 

Text-book  on  Roads  and  Pavements i2mo,  2  oo 

Tavlor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo,  8  oo 

Parti.     Non-metallic  Materials  of  Engineering  and  Metallurgy 8vo,  2  oo 

Part  II.     Iron  and  Steel 8vo»  3  50 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo»  2  SO 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  oo 

Turneaure  and  Maurer's  Principles  of  Reinforced  Concrete  Construction..  -8vo,  3  oo 

Waterbury's  Cement  Laboratory  Manual 12010,  i  oo 


Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials,  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,  2  oo 

Wood's  (M.  P.)  Rustless  Coatings:  Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  oo 

RAILWAY  ENGINEERING. 

Andrews's  Handbook  for  Street  Railway  Engineers 3x5  inches,  mor.  i   25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo 

Brooks's  Handbook  of  Street  Railroad  Location i6mo,  mor.  i  50 

Butt's  Civil  Engineer's  Field-book i6mo,  mor.  2  50 

CrandalTs  Railway  and  Other  Earthwork  Tables .  8vo,  i  50 

Transition  Curve i6mo,  mor.  i  50 

*  Crockett's  Methods  for  Earthwork  Computations 8vo,  i  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book i6mor  mor.  5  oo 

Dredge's  History  of  the  Pennsylvania  Railroad:    (1879) Paper,  5  oo 

Fisher's  Table  of  Cubic  Fards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide.  .  .  iGrno,  mor.  2  50 
Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments  8vo,  i   oo 

Ives    and  Hilts's   Problems  in  Surveying,  Railroad  Surveying  and  Geodesy 

i6mo,  mor.  i   50 

Molitor  and  Beard's  Manual  for  Resident  Engineers i6mo,  i  oo 

Nagle's  Field  Manual  for  Railroad  Engineers i6mo,  mor.  3  oo 

Philbrick's  Field  Manual  for  Engineers i6mo,  mor.  3  oo 

Raymond's  Railroad  Engineering.     3  volumes. 

VoL      I.  Railroad  Field  Geometry.     (In  Preparation.) 

VoL    II.  Elements  of  Railroad  Engineering 8vo,  3  50 

Vol.  III.  Railroad  Engineer's  Field  Book.     (In  Preparation.) 

Searles's  Field  Engineering i6mo,  mor.  3  oo 

Railroad  Spiral i6mo,  mor.  i  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  i  50 

*Trautwine's  Field  Practice  of  Laying   Out  Circular  Curves   for  Railroads. 

121110.  mor.  2  50 

*  Method  of  Calculating  the  Cubic  Contents  of  Excavations  and  Embank- 

ments by  the  Aid  of  Diagrams 8vo,  2  oo 

Webb's  Economics  of  Railroad  Construction Large  I2mo,  2  50 

Railroad  Construction i6mo,  mor.  5  oo 

Wellington's  Economic  Theory  of  the  Location  of  Railways Small  8vo,  5  oo 

DRAWING. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "                                                  Abridged  Ed 8vo,  i  50 

Coolidge's  Manual  of  Drawing 8vo.  paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  Engi- 
neers  Oblong  410,  2  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo,  2  50 

Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  oo 

Jamison's  Advanced  Mechanical  Drawing Svo,  2  oo 

Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery Svo,  i  50 

Part  n.    Form,  Strength,  and  Proportions  of  Parts Svo,  3  60 

Mac  Cord's  Elements  of  Descriptive  Geometry. Svo,  3  oc 

Kinematics ;  or,  Practical  Mechanism. Svo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams Svo,  i  50 

10 


McLeod's  Descriptive  Geometry Large  i2mo,  i  50 

*  Mahan's  Descriptive  Geometry  and  Stone-cutting 8vo,  i  50 

Industrial  Drawing.  (Thompson ) 8vo,  3  50 

Moyer's  Descriptive  Geometry  for  Students  of  Engineering 8vo,  2  oo 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  (R.  S.)  Manual  of  Topographical  Drawing.  (McMillan) 8vo,  2  50 

Smith  (A.  W.)  and  Marx's  Machine  Design 8vo,  3  oo 

*  Titsworth's  Elements  of  Mechanical  Drawing Oblong  8vo.  i   25 

Warren's  Drafting  Instruments  and  Operations i2mo,  i  25 

Elements  of  Descriptive  Geometry,  Shadows,  and  Perspective 8vo,  3  50 

Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing i2mo,  i  oo 

General  Problems  of  Shades  and  Shadows 8vo,  3  oo 

Manual  of  Elementary  Problems  in  the  Linear  Perspective  of  Form  and 

Shadow i2mo,  i  oo 

Manual  of  Elementary  Projection  Drawing i2mo,  i  50 

Plane  Problems  in  Elementary  Geometry i2mo,  r  25 

Problems,  Theorems,  and  Examples  in  Descriptive  Geometry. 8vo,  2  50 

Weisbach's     Kinematics    and    Power    of    Transmission.         (Hermann    and 

Klein) 8vo,  5  oo 

Wilson's  (H.  M.)  Topographic  Surveying 8vo,  3  50 

Wilson's  (V.  T.)  Free-hand  Lettering 8vo,  i  oo 

Free-hand  Perspective 8vo,  2  50 

Woolf's  Elementary  Course  in  Descriptive  Geometry Large  8vo,  3  oo 

ELECTRICITY  AND  PHYSICS. 

*  Abegg's  Theory  of  Electrolytic  Dissociation,     (von  Ende) i2mo,  i   25 

Andrews's  Hand-Book  for  Street  Railway  Engineering,  ...  .3X5  inches,  mor.  i  25 

Anthony  and  Brackett's  Text-book  of  Physics.     (Magie) Large  i2mo,  3  oo 

Anthony's  Theory  of  Electrical  Measurements.     (Ball) 12 mo,  i  oo 

Benjamin's  History  of  Electricity 8vo,  3  oo 

Voltaic  Cell 8vo,  3  oo 

Betts's  Lead  Refining  and  Electrolysis 8vo,  4  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.     (Boltwood).  .8vo,  3  oo 

*  Collins's  Manual  of  Wireless  Telegraphy i2mo,  i  50 

Mor.  2  oo 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

*  Danneel's  Electrochemistry.     (Merriam) i2mo,  i  25 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book  ....  i6mo,  mor.  5  oo 
Dolezalek's  Theory  of  the  Lead  Accumulator  (Storage  Battery),     (von  Ende) 

I2mo,  2  50 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess) 8vo,  4  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Gilbert's  De  Magnete.     (Mottelay) 8vo,  2  50 

*  Hanchett's  Alternating  Currents i2mo,  i  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  mor.  2  50 

*  Hobart  and  Ellis's  High-speed  Dynamo  Electric  Machinery 8vo,  6  oo 

Holman's  Precision  of  Measurements 8vo.  2  oo 

Telescopic   Mirror-scale  Method,  Adjustments,  and  Tests. ..  .Large  8vc,  75 

*  Karapetoff's  Experimental  Electrical  Engineering 8vo,  6  oo 

Kinzbrunner's  Testing  of  Continuous-current  Machines 8vo,  2  oo 

Landauer's  Spectrum  Analysis.     (Tingle) 8vo,  3  oo 

Le  Chatelier's  High-temperature  Measurements.  (Boudouard— Burgess)..  i2mo,  3  oo 

Lob's  Electrochemistry  of  Organic  Compounds.     (Lorenz) 8vo,  3  oo 

*  Lyndon's  Development  and  Electrical  Distribution  of  Water  Power  . . .  .8vo,  3  oo 

11 


*  Lyons's  Treatise  on  Electromagnetic  Phenomena.   Vols.  I.  and  II  8vo,  each,  6  oo 

*  Michie's  Elements  of  Wave  Motion  Relating  to  Sound  and  Light 8vo,  4  oo 

Morgan's  Outline  of  the  Theory  of  Solution  and  its  Results 121110,  i  oo 

*  Physical  Chemistry  for  Electrical  Engineers i2mo,  i  50 

Niaudet's  Elementary  Treatise  on  Electric  Batteries.     (Fishback).  .  .  .  i2mo,  2   50 

*  Norris's  Introduction  to  the  Study   of  Electrical  Engineering 8vo,  2  50 

*  Parshall  and  Hobart's  Electric  Machine  Design 4to,  half  mor.   12  50 

Reagan's  Locomotives:    Simple,  Compound,  and  Electric.      New  Edition. 

Large  i2mo,  3  50 

*  Rosenberg's  Electrical  Engineering.     (Haldane  Gee — Kinzbrunner).  ..  .8vo,  2  co 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     Vol.  1 8vo,  2  50 

Swapper's  Laboratory  Guide  for  Students  in  Physical  Chemistry i2mo,  i  oo 

*  Tinman's  Elementary  Lessons  in  Heat 8vo,  i  50 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Large  I2mo,  2  oo 

Ulke's  Modern  Electrolytic  Copper  Refining Svo.  3  oo 

LAW. 

'*  Brennan's  Handbook:    A  Compendium  of  Useful  Legal  Information  for 

Business  Men i6mo,  mor.  5 .  oo 

*  Davis's  Elements  or  Law Svo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States Svo,  7  oo 

*  Sheep,  7  SO 

*  Dudley's  Military  Law  and  the  Procedure  of  Courts- martial  . . .  .Large  i2mo,  2  50 

Manual  for  Courts-martial i6mo,  mor.  i  50 

Wait's  Engineering  and  Architectural  Jurisprudence Svo,  6  oo 

Sheep,  6  50 

Law  of  Contracts Svo,  3  oo 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  Svo  5  oo 

Sheep,  5  50 

MATHEMATICS. 

Baker's  Elliptic  Functions Svo,  i   50 

Briggs's  Elements  of  Plane  Analytic  Geometry.    (Bocher) i2mo,  i  oo 

*Buchanan's  Plane  and  Spherical  Trigonometry Svo,  i  oo 

Byerley's  Harmonic  Functions Svo,  i  oo 

Chandler's  Elements  of  the  Infinitesimal  Calculus 12 mo,  2  oo 

Coffin's  Vector  Analysis.          (In  Press.) 

Compton's  Manual  of  Logarithmic  Computations 121110,  i  50 

*  Dickson's  College  Algebra Large  i2mo,  i   50 

*  Introduction  to  the  Theory  of  Algebraic  Equations Large  i2mo,  i   25 

Emch's  Introduction  to  Protective  Geometry  and  its  Applications Svo,  2  50 

Fiske's  Functio  is  of  a  Complex  Variable Svo,  i  oo 

Halsted's  Elementary  Synthetic  Geometry Svo,  i   50 

Elements  of  Geometry Svo,  i  75 

*  Rational  Geometry i2mo,  i  50 

Hyde's  Grassmann's  Space  Analysis Svo,  i  oo 

*  Jonnson's  (J   B,)  Three-place  Logarithmic  Tables:  Vest-pocket  size,  paper,  15 

100  copies,  5  oo 

*  Mounted  on  heavy  cardboard,  8  X  10  inches,  25 

10  copies,  2  oo 
Johnson's  (W.  W.)  Abridged  Editions  of  Differential  and  Integral  Calculus 


Large  I2mo,  i  vol. 

Curve  Tracing  in  Cartesian  Co-ordinates 12 mo. 

Differential  Equations Svo. 

Elementary  Treatise  on  Differential  Calculus Large  i2mo, 

Elementary  Treatise  on  the  Integral  Calculus Large  I2mo, 


Theoretical  Mechanics I2mo,  3  oo 

Theory  of  Errors  and  the  Method  of  Least  Squares i2mo,  i  50 

Treatise  on  Differential  Calculus Large  12010,  3  oo 

12 


Johnson's  Treatise  on  the  Integral  Calculus Large  i2mo,    3  oo 

Treatise  on  Ordinary  and  Partial  Differential  Equations. . Large  i2mo,    3  50 
Karapetofi's  Engineering  Applications  of  Higher  Mathematics.      (In   Pre- 
paration.) 
Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory). .lamo,     2  oo 

*  Ludlow  and  Bass's  Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables 8vo,     3  oo 

Trigonometry  and  Tables  published  separately Each,     2  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,     i  oo 

Macfarlane's  Vector  Analysis  and  Quaternions 8vo,     i  oo 

McMahon's  Hyperbolic  Functions 8vo,     i  oo 

Manning's  Irrational  Numbers  and  their  Representation  by  Sequences  and 

Series i2mo,     i   25 

Mathematical  Monographs.     Edited  by  Mansfield  Merriman  and  Robert 

S.  Woodward Octavo,  each     i  oo 

No.  i.  History  of  Modern  Mathematics,  by  David  Eugene  Smith. 
No.  2.  Synthetic  Projeciive  Geometry,  by  George  Bruce  Halsted. 
No.  3.  Determinants,  by  Laenas  Gifford  Weld.  No.  4.  Hyper- 
bolic Functions,  by  James  McMahon.  IN'o.  <j.  Harmonic  Func- 
tions, by  William  E.  Byerly.  No.  6.  Grassmann's  Space  Analysis, 
by  Edward  W.  Hyde.  No.  7.  Probability  and  Theory  of  Errors, 
by  Robert  S.  Woodward.  No.  8.  Vector  Analysis  and  Quaternions, 
by  Alexander  Macfarlane.  No.  9.  Differential  Equations,  by 
William  Woolsey  Johnson.  No.  10.  The  Solution  of  Equations, 
by  Mansfield  Merriman.  No.  n.  Functions  of  a  Complex  Variable, 
by  Thomas  S.  Fiske. 

Maurer's  Technical  Mechanics 8vo,    4  oo 

Merriman's  Method  of  Least  Squares 8vo,    2  oo 

Solution  of  Equations 8vo,     i  oo 

Rice  and  Johnson's  Differential  and  Integral  Calculus.     2  vols.  in  one. 

Large  i2mo,     i  50 

Elementary  Treatise  on  the  Differential  Calculus Large  i2mo,     3  oo 

Smith's  History  of  Modern  Mathematics 8vo,     i  oo 

*  Vebien  and  Lennes's  Introduction  to  the  Real  Infinitesimal  Analysis  of  One 

Variable 8vo,     2  oo 

*  Waterbury's  Vest  Pocket  Hand-Book  of  Mathematics  for  Engine  rs. 

2s  X  5»  inches,  mor.     i  oo 

Weld's  Determinations 8vo,     i  co 

Wood's  Elements  of  Co-ordinate  Geometry 8vo,     2  oo 

Woodward's  Probability  azd  Theory  of  Errors 8vo,     i  oo 

MECHANICAL  ENGINEERING. 

MATERIALS   OF   ENGINEERING,   STEAM-ENGINES  AND  BOILERS. 

Bacon's  Forge  Practice i2mo,  i  50 

Baldwin's  Steam  Heating  for  Buildings I2mo,  2  50 

Bair's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "  "  "        Abridged  Ed 8vo,     i  50 

Benjamin's  Wrinkles  and  Recipes i2mo,    2  oo 

*  Burr's  Anciant  and  Modern  Engineering  and  the  Isthmian  Canal 8vo,     3  50 

Carpenter's  Experimental  Engineering 8vo,     6  oo 

Heating  and  Ventilating  Buildings 8vo,  4  oo 

Clerk's  Gas  and  Oil  Engine Large  12010,  4  oo 

Compton's  First  Lessons  in  Metal  Working i2mo,  i  50 

Comoton  and  De  Groodt's  Speed  Lathe i2mo,  i  50 

Coolidge's  Manual  of  Drawing 8vo,  paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  En- 
gineers  Oblong  4to,  2  50 

13 


Cromweil's  Treatise  on  Belts  and  Pulleys i2mo,  i  50 

Treatise  on  Toothed  Gearing i2mo,  i  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Flather's  Dynamometers  and  the  Measurement  of  Power, i2mo,  3  oo 

Rope  Driving I2mo,  2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,  i  25 

Goss's  Locomotive  Sparks 8vo,  2  oo 

Greene's  Pumping  Machinery.     (In  Preparation.) 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  mor.  2  50 

*  Hobart  and  Ellis's  High  Speed  Dynamo  Electric  Machinery 8vo,  6  oo 

Hutton's  Gas  Engine 8vo,  5  oo 

Jamison's  Advanced  Mechanical  Drawing 8vo,  2  oo 

Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Gas  Engine.      (In  Press.) 
Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo,  i   *o 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

Kent's  Mechanical  Engineers'  Pocket-book i6mo,  mor.  5  oo 

Kerr's  Power  and  Power  Transmission 8vo,  2  oo 

Leonard's  Machine  Shop  Tools  and  Methods 8vo,  4  oo 

*  Lorenz's  Modern  Refrigerating  Machinery.    (Pope,  Haven,  and  Dean) . .  .  8vo,  4  oo 
MacCord's  Kinematics ;   or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i   50 

MacFarland's  Standard  Reduction  Factors  for  Gases 8vo,  i  50 

Mahan's  Industrial  Drawing.     (Thompson) 8vo,  3  50 

Oberg's  Hand  Book  of  Small  Tools Large  i2mo,  3  oo 

*  Parshall  and  Hobart's  Electric  Machine  Design Small  4to,  half  leather,   12  50 

Peele's  Compressed  Air  Plant  for  Mines 8vo,  3  oo 

Poole's  Calorific  Power  of  Fuels 8vo,  3  oo 

*  Porter's  Engineering  Reminiscences,  1855  to  1882 8vo,  3  oo 

Reid's  Course  in  Mechanical  Drawing. 8vo,  2  oa 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Richard's  Compressed  Air i2mo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  (O.)  Press- working  of  Metals 8vo,  3  oo 

Smith  (A.  W.)  and  Marx's  Machine  Design 8vo,  3  oo 

Sorel '  s  Carbureting  and  Combustion  in  Alcohol  Engines .    (Woodward  and  Preston) . 

Large  i2mo,  3  oo 

Thurston's  Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics. 

i2mo,  i  oo 

Treatise  on  Friction  and  Lost  Work  in  Machinery  and  Mill  Work...  8vo,  3  oo 

Tillson's  Complete  Automobile  Instructor i6mo,  i  50 

mor.  2  oo 

Titsworth's  Elements  of  Mechanical  Drawing Oblong  8vo,  i   25 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

*  Waterbury's  Vest  Pocket  Hand  Book  of  Mathematics  for  Engineers. 

zfXst  inches,  mor.  i  oo 
Weisbach's    Kinematics    and    the    Power    of    Transmission.     (Herrmann — 

Klein) 8vo,  5  oo 

Machinery  of  Transmission  and  Governors.     (Herrmann — Klein)..  .8vo,  5  oo 

Wood's  Turbines 8vof  2  50 

MATERIALS  OF  ENGINEERING 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

*  Greene's  Structural  Mechanics 8vo,  2  50 

14 


Holley  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments,  and  Varnishes. 

Large  12010,  2  50 

Johnson's  Materials  of  Construction 8vo,  6  oo 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Maire's  Modern  Pigments  and  their  Vehicles I2mo,  2  oo 

Martens's  Handbook  on  Testing  Materials.     (Henning) 8vo,  7  50 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Mernman's  Mechanics  of  Materials 8vo,  5  oo 

*         Strength  of  Materials i2mo,  i  oo 

Metcaif's  Steel.      A  Manual  for  Steel-users I2mo,  2  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Materials  of  Machines I2mo,  i  oo 

Thurston's  Materials  of  Engineering 3  vols.,  8vo,  8  oo 

Parti.        Non-metallic  Materials  of  Engineering  and  Metallurgy ..  .8vo,  2  oo 

Part  II.      Iron  and  Steel 8vo,  3  50 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Treatise  on    the    Resistance    of    Materials  and    an  Appendix  on  the 

Preservation  of  Timber 8vo,  2  oo 

Wood's  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  oo 


STEAM-ENGINES  AND  BOILERS. 

Berry's  Temperature-entropy  Diagram.     Second  Edition,  Enlarged.  .  .  .i2mo,  2  oo 

Carnot's  Reflections  on  the  Motive  Power  of  Heat.     (Thurston) I2mo,  i  50 

Chase's  Art  of  Pattern  Making i2mo,  2  50 

Creighton's  Steam-engine  and  other  Heat-motors 8vo,  5  oo 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book i6mo,  mor.  5  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

*  Gebhardt's  Steam  Power  Plant  Engineering 8vo,  6  oo 

Goss's  Locomotive  Performance 8vo,  5  oo 

Hemenway's  Indicator  Practice  and  Steam-engine  Economy i2mo,  2  oo 

Button's  Heat  and  Heat-engines 8vo,  5  oo 

Mechanical  Engineering  of  Power  Plants 8vo,  5  oo 

Kent's  Steam  boiler  Economy 8vo,  4  oo 

Kneass's  Practice  and  Theory  of  the  Injector 8vo,  i  50 

MacCord's  Slide-valves Svo,  2  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  o<? 

Moyer's  Steam  Turbines Svo,  4  oo 

Peabody's  Manual  of  the  Steam-engine  Indicator i2mo.  i  50 

Tables  of  the  Properties  of  Saturated  Steam  and  Other  Vapors    Svo,  i  oo 

Thermodynamics  of  the  Steam-engine  and  Other  Heat-engines Svo,  5  oo 

Valve-gears  for  Steam-engines Svo,  2  50 

Peabody  and  Miller's  Steam-boilers Svo,  4  oo 

Pray's  Twenty  Years  with  the  Indicator Large  Svo,  2  50 

Pupin's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. 

(Osterberg) i2mo,  i  25 

Reagan's  Locomotives:    Simple,  Compound,  and  Electric.     New  Edition. 

Large  12 mo,  3  50 

Sinclair's  Locomotive  Engine  Running  and  Management i2mo,  2  oo 

Smart's  Handbook  of  Engineering  Laboratory  Practice I2mo,  2  50 

Snow's  Steam-boiler  Practice Svo,  3  oo 

Spangler's  Notes  on  Thermodynamics I2mo,  i  oo 

Valve-gears - Svo,  2  50 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering Svo,  3  oo 

Thomas's  Steam-turbines Svo,  4  oo 

15 


Thurston's  Handbook  of  Engine  and  Boiler  Trials,  and  the  Use  of  the  Indi- 
cator and  the  Prony  Brake Cvo,  5  oo 

Handy  Tables 8vo,  i  50 

Manual  of  Steam-boilers,  their  7  esigns,  Construction,  and  Cperation..8vo,  5  oo 

Thurston's   Manual  of  the  Steam-engine 2  vols.,  8vo,  10  oo 

Part  I.     History,  Structure,  and  Theory 8v?,  6  oo 

Fart  II.     Design,  Construction,  and  Operation 8vo,  6  oo 

Steam-boiler  Explosions  in  Theory  and  in  Practice i2mo,  i  50 

Wehrenfenning's  Analysis  and  Softening  of  Boiler  Feed-water  (Patterson)    Svo,  4  oo 

Weisbach's  Heat,  Steam,  and  Steam-engiaes.     (Du  Bois) Svo,  5  oo 

Whitham's  Steam-engine  Design ' 8vo,  5  oo 

Wood's  Thermodynamics,  Heat  Motors,  and  Refrigerating  Machines.  .  .8vo,  A  oo 

MECHANICS  PURE  AND  APPLIED. 

Church's  Mechanics  of  Engineering .8vo,  6  oo 

Notes  and  Examples  in  Mechanics Svo,  2  oo 

Dane's  Text-book  of  Elementary  Mechanics  for  Colleges  and  Schools.  .i2mo,  i   50 
Du  Bois's  Elementary  Principles  of  Mechanics: 

Vol.      I.     Kinematics Svo,  3  50 

Vol.    II.     Statics Svo,  4  od 

Mechanics  of  Engineering.     Vol.    I Small  4to,  7  50 

Vol.  II. Small  4to,  10  oo 

*  Greene's  Structural  Mechanics Svo,  2  50 

James's  Kinematics  of  a  Point  and  the  Rational  Mechanics  of  a  Particle. 

Large  I2mo,  2  oo 

*  Johnson's  (W.  W.)  Theoretical  Mechanics 12:110,  3  oo 

Lanza's  Applied  Mechanics Svo,  7  50 

*  Martin's  Text  Book  on  Mechanics,  Vol.  I,  Statics 12010,  i   25 

Vol.  2,  Kinemdu^s  and  Kinetics  .  .i2mo,  1  50 

Maurer's  Technical  Mechanics Svo,  4  oo 

*  Merriman's  Elements  of  Mechanics I2mo,  i  oo 

Mechanics  of  Materials Svo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics Svo,  4  oo 

Robinson's  Principles  of  Mechanism Svo,  3  oo 

Sanborn's  Mechanics  Problems Large  i2mo,  i  50 

Schwamb  and  Merrill's  Elements  of  Mechanism Svo,  3  oo 

Wood's  Elements  of  Analytical  Mechanics Cvo,  3  oo 

Principles  of  Elementary  Mechanics i2mo,  i  25 

MEDICAL. 

*  Abderhalden's  Physiological  Chemistry  in  Thirty  Lectures.    (Hall  and  Defren) 

Svo,  5  oo 

von  Behring's  Suppression  of  Tuberculosis.     (Bolduan) i2mo,  i  oo 

*  Bolduan's  Immune  Sera i2mo,  i  50 

Bordet  s  Contribution  to  Immunity.     (Gay).     (In  Preparation.) 

Davenport's  Statistical  Methods  with  Special  Reference  to  Biological  Varia- 
tions  i6mo,  mor.  i  50 

Ehrlich's  Collected  Studies  on  Immunity.     (Bolduan) Svo,  6  oo 

*  Fischer's  Physiology  of  Alimentation Large  i2mo,  cloth,  2   oo 

de  Fursac's  Manual  of  Psychiatry.     (Rosanoff  and  Collins) Large  i2mo,  2  50 

Hammarsten's  Text-book  on  Physiological  Chemistry.     (Mandel) Svo,  4  oo 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  ..Svo,  i   25 

Lassar-Cohn's  Practical  Urinary  Analysis.     (Lorenz) i2mo,  i  oo 

Mandel's  Hand  Book  for  the  Bi— Chemical  Laboratory .  .  i2mo,  i  50 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.     (Fischer) i2mo,  i  25 

*  Pozzi-Escot's  Toxins  and  Venoms  and  their  Antibodies.     (Cohn) I2mo,  i  oo 

Rostoski's  Serum  Diagnosis.     (Bolduan) i2mo,  i  oo 

Ruddiman's  Incompatibilities  in  Prescriptions Svo.  2  oo 

Whys  in  Pharmacy I2mo,     i  oo 

16 


Salkowski's  Physiological  and  Pathological  Chemistry.     (Orndorff) 8vo,  2  SO 

*  Satterlee's  Outlines  of  Human  Embryology I2mo,  i  25 

Smith's  Lecture  Notes  on  Chemistry  for  Dental  Students 8vo,  2  50 

Steel's  Treatise  on  the  Diseases  of  the  Dog 8vo,  3  50 

*  Whipple's  Typhoid  Fever Large  i2mo,  3  oo 

Woodhull's  Notes  on  Military  Hygiene i6mo,  i  50 

*  Personal  Hygiene I2mo,  i  oo 

Worcester  and  Atkinson's  Small  Hospitals  Establishment  and  Maintenance, 

and  S  ggestions  for  Hospital  Architecture,  with  Plans  for  a  Small 

Hospital i2mo,  i  25 

METALLURGY, 

Betts's  Lead  Refining  by  Electrolysis 8vo,  4  oo 

Holland's  Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  Used 

in  the  Practice  of  Moulding i2mo,  3  oo 

Iron  Founder 121110,  2  50 

Supplement i2mo,  2  50 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo,  i  oo 

Goesel's  Minerals  and  Metals:  A  Reference  Book i6mo,  mor.  3  oo 

*  Iles's  Lead-smelting i2mo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

LeChatelier's  High-temperature  Measurements.   (Boudouard — Burgess)  i2mo,  3  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Miller's  Cyanide  Process i2mo,  i  oo 

Minet's  Production  of  Aluminium  and  its  Industrial  Use.     (Waldo)  .  .  ,i2mo,  2  50 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc) 8vo,  4  oo 

Ruer's  Elements  of  Metallography.     (Mathewson)     (In  Press.) 

Smith's  Materials  of  Machines I2mo,  i  oo 

Tate  and  Stone's  Foundry  Practice i2mo,  2  50 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo,  8  oo 

Part  I.         Non-metallic  Materials  of  Engineering  and  Metallurgy  .  .  .  8vo,  2  oo 

Part  II.       Iron  and  Steel 8vo,  3  50 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

West's  American  Foundry  Practice i2mo,  2  50 

Moulder's  Text  Book    i2mo,  2  50 

Wilson's  Chlorination  Process i2mo,  i  50 

Cyanide  Processes i2mo,  i  50 

MINERALOGY. 

Barringer's  Description  of  Minerals  of  Commercial  Value Oblong,  mor.  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo,  3  oo 

Boyd's  Map  of  Southwest  Virginia Pocket-book  form.  2  oo 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  i  50 

Brush's  Manual  of  Determinative  Mineralogy.     (Penfield) ,. 8vo,  4  oo 

Butter's  Pocket  Hand-Book  of  Minerals i6mo,  mor.  3  oo 

Chester's  Catalogue  of  Minerals 8vo,  paper,  i  oo 

Cloth,  i  25 

*  Crane's  Gold  and  Silver 8vo,  5  oo 

Dana's  First  Appendix  to  Dana's  New  "  System  of  Mineralogy. .".  .Large  8vo,  i  oo 

Manual  of  Mineralogy  and  Petrography i^mo  2  oo 

Minerals  and  How  to  Study  Them i2mo,  i  50 

System  of  Mineralogy Large  8vo,  half  leather,  12  50 

Text-book  of  Mineralogy 8vo,  4  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects I2mo,  i  oo 

Eakle's  Mineral  Tables 8vo,  i  25 

Stone  and  Clay  Products  Used  in  Enginearing.     (In  Preparation.) 
17 


Egleston's  Catalogue  of  Minerals  and  Synonyms 8vo,  2  50 

Goesel's  Minerals  and  Metals :     A  Reference  Book i6mo ,  mor.  3  oo 

Groth's  Introduction  to  Chemical  Crystallography  (Marshall) 12 mo,  i  25 

*  Iddings's  Rock  Minerals    8vo,  5  oo 

Johannsen's  Determination  of  Rock-forming  Minerals  in  Thin  Sections 8vo,  4  oo 

*  Martin's  Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe,  izmo,  60 
Merrill's  Non-metallic  Minerals:  Their  Occurrence  and  Uses 8vo,  4  oo 

Stones  for  Building  and  Decoration 8vo,  5  oo 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  50 
Tables    of    Minerals,    Including    the  Use  of  Minerals  and  Statistics  of 

Domestic  Production 8vo,  i  oo 

*  Pirsson's  Rocks  and  Rock  Minerals i2mo,  2  50 

*  Richards's  Synopsis  of  Mineral  Characters. i2mo,  mor.  i   25 

*  Ries's  Clays:  Their  Occurrence,  Properties,  and  Uses 8vo,  5  oo 

*  Tollman's  Text-book  of  Important  Minerals  and  Rocks 8vo,  2  oo 

MINING. 

*  Beard's  Mine  Gases  and  Explosions Large  12010,  3  oo 

Boyd's  Map  of  Southwest  Virginia Pocket-boo*  rorm  2  oo 

Resources  of  Southwest  Virginia 8vo,  3  oo 

*  Crane's  Gold  and  Silver    8vo,  5  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo  i  oo 

Eissler's  Modern  High  Explosives 8vo,  4   ->o 

Goesel's  Minerals  and  Metals :     A  Reference  Book i6mo,  mor.  3  oo 

Ihlseng's  Manual  of  Mining 8vo,  5  oo 

*  Iles's  Lead-smelting i2mo,  2  50 

Miller's  Cyanide  Process i2mo,  i  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Peele's  Compressed  Air  Plant  for  Mines 8vo,  3  oo 

Riemer's  Shaft  Sinking  Under  Difficult  Conditions.     (Corning  and  Peele) . .  .8vo,  3  oo 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc) 8vo,  4  oo 

*  Weaver's  Military  Explosives 8vo,  3  oo 

Wilson's  Chlorination  Process i2mo,  i  50 

Cyanide  Processes i2mo,  i  50 

Hydraulic  and  Placer  Mining.     2</  edition,  rewritten i2mo,  2  50 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation 12 mo,  125 

SANITARY  SCIENCE. 

Association  of  State  and  National  Food  and  Dairy  Departments,  Hartford  Meeting, 

1906 8vo,  3  oo 

Jamestown  Meeting,  1907 8vo,  3  oo 

*  Bashore's  Outlines  of  Practical  Sanitation i2mo,  i  25 

Sanitation  of  a  Country  House 12010,  i  oo 

Sanitation  of  Recreation  Camps  and  Parks i2mo,  i  oo 

Folwell's  Sewerage.  (Designing,  Construction,  and  Maintenance) 8vo,  3  oo 

Water-supply  Engineering 8vo,  4  oo 

Fowler's  Sewage  Works  Analyses i2mo,  2  oo 

Fuertes's  Water-filtration  Works i2mo,  2  50 

Water  and  Public  Health i2mo,  i  50 

Gerhard's  Guide  to  Sanitary  Inspections i2mo,  i  50 

*  Modern  Baths  and  Bath  Houses 8vo,  3  oo 

Sanitation  of  Public  Buildings "mo,  i  50 

Hazen's  Clean  Water  and  How  to  Get  It Large  i2mo,  i  50 

Filtration  of  Public  Water-supplies 8vo,  3  oo 

Kinnicut,  Winslow  and  Pratt's  Purification  of  Sewage.     (In  Press.) 

Leach's   Inspection   and   Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,  7  oo 

18 


Mason's  Examination  of  Water.     (Chemical  and  Bacteriological) i2mo,     i  25 

Water-supply.  (Considered  Principally  from  a  Sanitary  Standpoint; . .  8vo,    4  oo 

*  Merriman's  Elements  of  Sanitary  Engineering 8vo,        oo 

Ogden's  Sewer  Design i2mo,        oo 

Parsons's  Disposal  of  Municipal  Refuse 8vo,        oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis i2mo, 

*  Price's  Handbook  on  Sanitation i2mo, 

Richards's  Cost  of  Cleanness.     A  Twentieth  Century  Problem i2mo, 


Cost  of  Food.     A  Study  in  Dietaries i2mo, 

Cost  of  Living  as  Modified  by  Sanitary  Science 


So 
50 
oo 
oo 
oo 

Cost  of  Shelter.    A  Study  in  Economics 1 2mo,  i  oo 

*  Richards  and  Williams's  Dietary  Computer 8vo,  i  50 

Richards  and   Woodman's  Air,   Water,  and  Food  from  a  Sanitary  Stand- 
point  8vo,  2  oo 

Rideal's    Disinfection  and  the  Preservation  of  Food 8vo,  4  oo 

Sewage  and  Bacterial  Purification  of  Sewage 8vo,  4  oo 

Soper's  Air  and  Ventilation  of  Subways  . .Large  12 mo,  2  50 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Venable's  Garbage  Crematories  in  America 8vo,  2  oo 

Method  and  Devices  for  Bacterial  Treatment  of  Sewage 8vo,  3  oo 

Ward  and  Whipple's  Freshwater  Biology 121110,  2  50 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Typhod  Fever Large  i2tno,  3  oo 

Value  of  Pure  Water Large  i2mo,  i  oo 

Winslow's  Bacterial  Classification i2mo,  2  50 

Winton's  Microscopy  of  Vegetable  Foods 8vo,  7  50 

MISCELLANEOUS. 

Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  8vo,  i  50 

Fen-el's  Popular  Treatise  on  the  Winds 8vo,  4  oo 

Fitzgerald's  Boston  Machinist i8mo,  i  oo 

Gannett's  Statistical  Abstract  of  the  World 24mo,  75 

Haines's  American  Railway  Management i2mo,  2  50 

*  Hanusek's  The  Microscopy  of  Technical  Products.    (Winton) 8vo,  5  oo 

Owen's  The  Dyeing  and  Cleaning  of  Textile  Fabrics.     (Standage).     (In  Press.) 
Ricketts's  History  of  Rensselaer  Polytechnic  Instituta  1824-1894. 

Large  12 mo,  3  oo 

Rotherham's  Emphasized  New  Testament 0 Large  8vo,  2  oo 

Standage's  Decoration  of  Wood,  Glass,  Metal,  etc i2mo,  2  oo 

Thome's  Structural  and  Physiological  Botany.    (Bennett) i6mo,  225 

Westermaier's  Compendium  of  General  Botany.     (Schneider) 8vo,  2  oo 

Winslow's  Elements  of  Applied  Microscopy I2mo,  i  50 


HEBREW  AND  CHALDEE  TEXT-BOOKS. 

Crreen's  Elementary  Hebrew  Grammar i2mo,     i  25 

Qesenius's  Hebrew  and  Chaldee  Lexicon  to  the  Old  Testament  Scriptures. 

(Tregelles) Small  410,  half  mor.    5  oo 

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